This Article develops a European perspective on sustainable mobility, a concept still underexamined in legal scholarship, and argues that meeting today’s mobility needs while preserving ecological foundations for future generations will not occur without deliberate regulatory intervention. After clarifying the evolution of the core concepts of sustainability, mobility, and sustainable mobility, the Article shows how international, European, and Austrian law have progressively incorporated sustainability goals in the transport sector. It then proposes a taxonomy of financial incentives–from subsidies and tax breaks to behavioral nudges—and evaluates their effectiveness, emphasizing the need for flexible, context-specific regulatory instruments. Applying these insights to self-driving cars, the Article demonstrates that technological innovation alone cannot deliver sustainable mobility and that proactive, sustainability-oriented regulation remains essential. The Article concludes with several proposals for reform aimed at steering technological and behavioral change toward a genuinely sustainable mobility system.

Introduction

Arnold Schwarzenegger put forward the following scenario on his Facebook page on December 7, 2015:

There are two doors. Behind Door Number One is a completely sealed room, with a regular, gasoline-fueled car. Behind Door Number Two is an identical, completely sealed room, with an electric car. Both engines are running full blast. I want you to pick a door to open, and enter the room and shut the door behind you. You have to stay in the room you choose for one hour. You cannot turn off the engine. You do not get a gas mask.

We all know what we would choose in this situation. Yet many people still prefer to use a combustion engine in their daily lives. Because air pollution does not affect most people as directly as in the scenario described, it is not an immediate concern for many. Similarly, climate change is often not considered at the individual level. The law thus provides an important tool in creating incentives and shaping individual behavior to contribute to common goals.

The main goal of this Article is to present a European perspective on the concept and potential for implementation of sustainable mobility, a topic still scarcely discussed in legal scholarship. The Article understands sustainable mobility as a commitment to meeting our mobility needs today in a way that preserves the ecological basis for future generations. It argues that sustainable mobility will not take off by itself. Instead, regulators in Europe and beyond should deploy policies—including a wide range of flexible and context specific financial incentives—to incentivize its adoption.

The Article is structured as follows. Part I discusses the evolution of core concepts: sustainability, mobility, and sustainable mobility. Part II provides an overview of how international, European, and national law in Austria have progressively included and promoted sustainable mobility. Part III proposes a taxonomy of financial incentives associated with sustainable mobility and analyzes their efficiency. Part IV applies these insights to the example of self-driving cars to illustrate the continuing need for regulation and policy adaptation, despite the sustainability assumptions attached to newer technologies. The Article concludes, in Part V, with several proposals for reform.

I. Terminology

A. Sustainability

The term sustainability has its roots in the late 17th and early 18th century. Even today, many people still refer to Carl von Carlowitz, who in 1713 spoke of the “continuous and sustainable use” of timber cultivation and thus popularized the concept of sustainability in the German-speaking world.¹ Carl von Carlowitz, Sylvicultura oeconomica oder Haußwirthliche Nachricht und Naturmäßige Anweisung zur Wilden Baum-Zucht 105 (1713) (translation—unless otherwise stated—always by the author). See Karl-Friedrich Weber & Friedhart Knolle, Einer mitteldeutschen Waldlegende auf der Spur: Wurde die Nachhaltigkeit im Harz erfunden?, 1 Sachsen-Anhalt-Journal 5, 5-7 (2023), https://journal.lhbsa.de/cpt-articles/harz-hans-carl-von-carlowitz-nachhaltigkeit-forstwirtschaft-mitteldeutschland (explaining that the term “sustainability,” or in German “Nachhaltigkeit,” had been used in relation to forestry before Carlowitz); see also Paul Warde, The Invention of Sustainability: Nature and Destiny, c. 1500 – 1870 4 (2018) (“[W]hat we might call sustainability, which previously had not registered in public debate at all, or only in a rather indirect manner, emerged at the end of the early modern period, after the 1740s, as an urgent problem that society had to resolve.”).
The idea is both plausible and simple. If wood—a resource of great industrial importance at the time—is to be used over the long term, it must be used economically; forests should not be depleted faster than they can regenerate.²Stephan Rammler, Nachhaltige Mobilität: Gestaltungsszenarien und Zukunftsbilder, in Handbuch Verkehrspolitik 2. Auflage, 902, 902 (Oliver Schöller, Weert Canzler & Andreas Knie eds., 3rd ed. 2016).
Although this idea is fundamental and likely has even earlier origins,³See, e.g., Bert J. M. de Vries, Sustainability Science 10, 62 (2nd ed. 2024) (stating that the “underlying concern has ancient roots, under various names”); see also Saleem H. Ali, Sustainability. A Very Short Introduction 3 (2025) (“Many indigenous traditions have notions of balance for maintaining their tribal resource base through some norms or traditions.”); Christoph M. Stoll, Nachhaltigkeit im Recht im Wandel der Zeit, in Nachhaltigkeit im Spiegel des Rechts 27 (Malte Kramme & Emanuel Ponholzer eds., 2023). On medieval customary law, see Berndt Marquard, Umwelt und Recht in Mitteleuropa. Von den großen Rodungen des Hochmittelalters bis ins 21. Jahrhundert III (2003); see also Ulrich Grober, Die Entdeckung der Nachhaltigkeit. Kulturgeschichte eines Begriffs (3rd ed. 2010); Die Erfindung der Nachhaltigkeit. Leben, Werk und Wirkung des Hans Carl von Carlowitz (Sächsische Hans-Carl-von-Carlowitz-Gesellschaft e. V., 2013). Cf. Warde, supra note 1, at 4 (on the conscious idea or political concept of society’s dependence on a sustainable economy).
what is special about the forestry sector is that this idea was enshrined in law at an early stage.⁴See, e.g., Richard Hölzl, Historicizing Sustainability: German Scientific Forestry in the Eighteenth and Nineteenth Centuries, 19 Science as Culture 431, 438 (2010) (“The beginnings of sustainable forestry were closely connected to the early modern rise of iron and glass manufacturing as well as to salt production. Sustainable forestry continued a line of thought that had appeared in earlier centuries, for instance in the notion of the ‘eternal forest’”); Georg Meister, Der ‘ewige Wald’ der Saline Reichenhall, in Salz macht Geschichte 179, 179 (Manfred Treml ed., 1995); Peter-Michael Steinsiek, Nachhaltigkeit auf Zeit. Waldschutz im Westharz vor 1800 (1999) (PhD Dissertation, Göttingen University). See also Stoll, supra note 3, at 30-39, on sustainability as a guiding principle in forest law with examples ranging from “Venetian forest policy and legislation” to the “[s]ustainability principle in the forest and forestry regulations of the Habsburg Monarchy.”

For the current understanding of sustainability, two turning points in the world history of ecology are particularly relevant. The first occurred around the 1970s, and is referred to as the “ecological revolution,” which is characterized by holistic, networked thinking.⁵See on this, the social scientist Rammler, supra note 2, at 901. Cf. the social historian Joachim Radkau, Die Ära der Ökologie. Eine Weltgeschichte 124, 172 (2011). In a kind of “chain reaction,” different “subject areas, activities and political arenas” are combined under the label of environmental protection and the concept of environmental protection is linked with nature conservation, animal, forest and water protection, air pollution control and occupational and consumer protection.
Since the 1980s, the term has experienced a surge in popularity, with some calling it a “topic of the century.”⁶ Felix Ekardt, Theorie der Nachhaltigkeit [Theory of Sustainability] 66 (3rd ed. 2021). See also de Vries, supra note 3, at 4 (speaking of “one of the leading aspirations of humankind in the twenty-first century.”).
In particular, the 1987 Brundtland Report of the United Nations World Commission on Environment and Development, defined sustainable development in the following terms:

Humanity has the ability to make development sustainable to ensure that it meets the needs of the present without compromising the ability of future generations to meet their own needs.⁷ World Commission on Environment and Development, Our Common Future: Report of the World Commission on Environment and Development § 27 (1987).

Accordingly, sustainability means meeting current needs in such a way that this is not at the expense of the needs of future generations.⁸Id.
In other words, a society should not destroy the ecological basis on which it depends.⁹ Warde, supra note 1, at 5.
Around 1990, this insight marked a second turning point, when the environmental concerns were “linked to the issue of intra- and inter-generational justice, and thus to the international development policy discourse.”¹⁰ Rammler, supra note 2, at 902, see also Radkau, supra note 5, at 488.
This is where the “global success story” of the concept of sustainability finally began, and took its course with the 1992 United Nations Conference on Environment and Development, also known as the Rio Earth Summit.¹¹ Rammler, supra note 2, at 902.
At Rio, the definition of sustainability was expanded to include the so-called “three-pillar model,” which recognizes a social, economic, and ecological dimension to sustainability, and links environmental and development efforts. Culminating this trend, the “2030 Agenda,” announced by the United Nations in 2015, articulated 17 sustainable development goals.¹²G.A. Res. 70/1, U.N. Doc. A/Res/70/1 (Oct. 21, 2015), Transforming our world: the 2030 Agenda for Sustainable Development, https://docs.un.org/en/A/RES/70/1; cf. Jannis Bertling, et al., Vorwort, in Nachhaltigkeit im Wandel 5 (Jannis Bertling, et al., eds., 2024).
Yet, despite these developments, the ecological dimension of sustainability still seems to have a priority over the social and economic dimensions.¹³See, e.g., Markus P. Beham, Berthold Hofbauer & Berthold Lindner, Was ist Nachhaltigkeitsrecht?, 1 Zeitschrift Nachhaltigkeitsrecht (2021).

In particular, the idea of enabling future generations to meet their needs enjoyed growing prominence. Sustainability thus became a central political concept, serving as an overarching model for addressing the development crisis in the Global South, and the understanding of sustainable development. At the same time, sustainability also became central to addressing the environmental problems of the Global North.¹⁴ Ekardt, supra note 6, at 66.
While these phenomena overlap considerably, there are also significant differences between them. For example, sustainable development encompasses social and economic dimensions, which can conflict with ecological sustainability. While the economic and social aspects of sustainability are more important for the Global South, the environmental concerns are stronger in the Global North. The fact that these two very different phenomena are referred to with one and the same term suggests that although the concept of sustainability is able to cover a wide range, this comes at a cost of concrete, actionable implications. Thus, critical voices have asked whether sustainability is just another “fashionable topic.”¹⁵Cf., Ferdinand Kerschner, Nachhaltigkeit in der Rechtswissenschaft – neue Teildisziplin oder nur ein Modethema? Ein kursorischer Abriss, in Nachhaltigkeit im Spiegel des Rechts 15, 23 (Malte Kramme & Emanuel Ponholzer eds., 2023) (“Sustainability law is neither a new (!) subdiscipline nor just (!) a fashionable topic.”); Malte Kramme, Nachhaltiges Recht, in Nachhaltigkeit im Spiegel des Rechts 3, 4 (Malte Kramme & Emanuel Ponholzer eds., 2023) (“Cross-cutting issue rather than fashionable topic”).

One must concede that there are several difficulties in practical application of sustainability as a concept. Ensuring that future generations can satisfy similar needs is intuitively convincing, especially when we think of categories such as “children” or “grandchildren.” But on closer inspection, uncertainties are attached to the very definition of those terms. Who are the future generations specifically?¹⁶See Stephen Humphreys, Against Future Generations, 33 Eur. J. Int. L. 1061, 1061(2022).
Do they include children who are already alive or only those who are yet to be born? How many generations are, or should be, covered? Till what time in the future should the satisfaction of needs be ensured? Is it 100 years, 200 years, or till infinity? A further difficulty lies in the fact that it is not clear whether only the future generations of a particular jurisdiction (e.g., Austria), a particular region (e.g., Europe), or the whole of humanity are covered. These are just a few examples that show that it is difficult to derive concrete consequences or actionable instructions from the concept of sustainability.¹⁷A paradigmatic example of this is Martin Held, Nachhaltige Mobilität, in Handbuch Verkehrspolitik 851, 867 (Oliver Schöller, Weert Canzler & Andreas Knie eds., 2007). While the concept of sustainability was gaining acceptance, a global take-off of air traffic took place. Accordingly, Held also identifies the following basic trend: “Since the beginning of the discussion about sustainable mobility, the actual development has continued unabated in the direction of unsustainability, apart from certain individual aspects.” Id.

This does not mean that the concept as such is meaningless, but it needs to be made more concrete in order to achieve specific results.¹⁸Cf. Margaretha Wewerinke-Singh, Ayan Garg & Shubhangi Agarwalla, In Defence of Future Generations: A Reply to Stephen Humphreys, 34 Eur. J. Int. L. 651, 651 (2023); Peter Lawrence, International Law Must Respond to the Reality of Future Generations: A Reply to Stephen Humphreys, 34 Eur. J. Int. L. 669, 669 (2023).
For example, in order to grasp the needs of future generations, assumptions can be made by borrowing from the needs of current generations. Despite these ambiguities, sustainability—although not a genuinely legal concept—was taken up by numerous international soft law instruments, and is now a central objective in the law of the European Union (EU), and its member states, such as Austria.¹⁹See infra Part II.C.
In both EU and domestic law, the international law definition is generally followed. This certainly underlines the importance of the concept in international law even though, to date, not a single international agreement includes a binding, universally accepted definition of the term.

B. Mobility

The concept of mobility is probably even more present in everyday language than that of sustainability. Physical, mental and, in modern times, social mobility, are widely known. If we understand mobility in such general terms, the idea has been around since time immemorial. Yet, in more strict linguistic terms, the origin of the concept of mobility—similar to that of sustainability—can be traced back to the 18th century.²⁰This is true at least in the German language. See the word progression curve for the term “mobility” (Mobilität in German) in the online corpus of the German Text Archive (DTA), which includes a DTA core corpus comprising “around 1500 titles from the period from around 1600 to 1900, which were selected due to their outstanding significance for the development of the German language or the respective genres and scientific disciplines.” DWDS-Verlaufskurve für „Mobilität”, erstellt durch das Digitale Wörterbuch der deutschen Sprache, Digitales Wörterbuch der deutschen Sprache (July 12, 2025), https://www.dwds.de/r/plot/?view=1&corpus=dta%2Bdwds&norm=date%2Bclass&smooth=spline&genres=0&grand=1&slice=10&prune=0.05&window=3&wbase=0&logavg=0&logscale=0&xrange=1600%3A1999&q1=Mobilit%C3%A4t.

Up until the 1970s, the term mobility was primarily used in the social sciences. Transport sciences, for example, predominantly spoke of transport “as a term for the entirety of all processes that serve to overcome space.”²¹ Rammler, supra note 2, at 904 (citing Walter Linden, Dr. Gablers Verkehrs-Lexikon 1646 (1966)).
Like sustainability, the concept of mobility has become increasingly popular over time.²²Id., at 904; Hasso Spode, Mobilität, Reisen, Tourismus. Transformationen der Terminologie zwischen Fremdenverkehrslehre und Mobility Turn, in Die Gesellschaft auf Reisen – eine Reise in die Gesellschaft 23 (Harald Pechlaner & Michael Volgger eds., 2017).
Since the 1990s in particular, the concept of mobility has been increasingly used to focus on the transportation of things and people as an object of analysis.²³See Colin Divall, Mobilities and Transport History, in The Routledge Handbook of Mobilities 36 (Peter Adey, et al., eds., 2014). The concept of mobility is dazzling; it is used to analyze numerous phenomena. For example, “social mobility” is used to describe–in simple terms–migration research. For example, the sociologist John Urry, argues that the concept of mobility is a central category of analysis for borderless societies. See John Urry, Sociology Beyond Societies. Mobilities for the Twenty-First Century (2000). For a sample of the enormous variety of academic analyses of mobility, see The Moving City: Processions, Passages and Promenades in Ancient Rome (Ida Östenberg, Simon Malmberg Jonas Bjørnebye eds., 2015); Tanuja Kothiyal, Nomadic Narratives: A History of Mobility and Identity in the Great Indian Desert (2016); Mobility in the Early Middle Ages, and Beyond – Mobilität im Frühmittelalter und darüber hinaus Interdisciplinary Approaches – Interdisziplinäre Zugänge (Laury Sarti & Helene von Trott zu Solz eds., 2025); Mobile People, Mobile Law: Expanding Legal Relations in a Contracting World (Franz von Benda-Beckmann, Keebet von Benda-Beckmann & Anne Griffiths eds., 2005) (focusing on the legal aspects of mobility).
Since the mid-1990s transportation and mobility (in German Verkehr and Mobilität) have been used synonymously.²⁴ Rammler, supra note 2, at 904.

However, equating mobility and transportation is considered too narrow by the social science-based transportation sciences.²⁵It is also interesting to note that the term seems to have almost exclusively positive connotations in everyday language. While most people are quite familiar with “traffic congestion,” the term “mobility congestion” is rarely used. “Traffic accidents” happen every day, but “mobility accidents” are unknown. See Rammler, supra note 2, at 904.
These disciplines promote a broad understanding of mobility which should encompass the “accessibility of facilities and communication access points in a global society.”²⁶ Rammler, supra note 2, at 905 (citing Eckhard Kutter, Mobilität als Determinante städtischer Lebensqualität, in Verkehr in Ballungsräumen 66 (Wilhelm Leutzbach ed., 1975)); see also Martin Held, Nachhaltige Mobilität, in Handbuch Verkehrspolitik 851 (Oliver Schöller, Weert Canzler & Andreas Knie eds., 2007). Cf. on mobility research as “research on movement and mobility in space,” Konrad Götz, Nachhaltige Mobilität, in Handbuch Umweltsoziologie 325, 325-343 (Matthias Groß ed., 2011) (referring to an incipient comprehensive sociological discourse on “mobilities.”). Despite this broad understanding, this article focuses on the transport-related aspect of sustainable mobility, particularly on self-driving cars.
As early as the 1970s, there were critical voices that did not want mobility to be defined exclusively as motorized travel.²⁷Rammler, supra note 2, at 904 (citing Eckhard Kutter, Mobilität als Determinante städtischer Lebensqualität, in Verkehr in Ballungsräumen 64 (Wilhelm Leutzbach ed., 1975).
This also seems to have been generally accepted in the legal sciences.²⁸See, e.g., Edmund Brandt, Vorstudien zum Mobilitätsrecht (2016).

In strictly normative terms, however, mobility is not a central analytical concept. Nevertheless, due to the wide range of phenomena covered by the term, it comes into contact with several fundamental rights, primarily the right to freedom of movement, which is considered a central human and fundamental right in Austria and beyond.²⁹Staatsgrundgesetz, art. 4(1) (Austria); Protocol No. 4 to the Convention for the Protection of Human Rights and Fundamental Freedoms, securing certain rights and freedoms other than those already included in the Convention and in the first Protocol thereto, Sep. 16, 1963, Europ. T.S. No. 046, art 2(1); Charter of Fundamental Rights of the European Union, art. 45, 2012 O.J. C 326/391, at 404 [hereinafter Charter].
In EU law, mobility is embedded within the so-called “four fundamental freedoms,” which guarantee the free movement of persons,³⁰Consolidated Version of the Treaty on European Union art. 3(2), 2012 O.J. C 326/13, at 17 [hereinafter TEU]; Consolidated Version of the Treaty on the Functioning of the European Union arts. 21, 45, 2012 O.J. C 326/47, at 28, 40 [hereinafter TFEU].
goods,³¹TFEU, supra note 30, art. 34, 2012 O.J. C 326/47, at 35.
services,³²Id. art. 56.
and capital,³³Id. art. 63.
and which are the central pillars of the EU internal market. In addition, there are also advocates of a fundamental right to mobility,³⁴Cf. Michael Ronellenfitsch, Mobilität: Vom Grundbedürfnis zum Grundrecht?, 9 Deutsches Autorecht 321, 321 (1992); Michael Ronellenfitsch, Die Verkehrsmobilität als Grund und Menschenrecht – Betrachtungen zur “zirkulären” Mobilität in der Europäischen Union, 44 Jahrbuch des öffentlichen Rechts der Gegenwart 167, 168 (1996).
which, however, is viewed critically by the prevailing opinion in the German-speaking legal discourse.³⁵See e.g., Stefan Martini, Gibt es ein Subjektives Recht auf Öffentlichen Verkehr? Grundrechte der Daseinsvorsorge (Wissenschaftszentrum Berlin für Sozialforschung, Discussion Paper SP III 2006-103, 2006), https://nbn-resolving.org/urn:nbn:de:0168-ssoar-114588. Cf. on Austria and the denial of a mobility service guaranteed by the state under fundamental rights, Dragana Damjanovic & Oliver Peck, Möglichkeiten Einer Rechtlichen Verankerung der Mobilitäts(Service)Garantie 6 (Österreichische Forschungsförderungs-GmbH Report, 2022), https://projekte.ffg.at/anhang/63368251d8085_M5.2%20Rechtliche%20Verankerung%20Mobilit%C3%A4tsgarantie.pdf.

For clarity’s sake, moving forward, I will mainly use the narrow definition of the concept of mobility, that is, equating it with transport. This is not intended to exclude the previously mentioned understanding of mobility as “accessibility” but to move it into the background for the time being in order to be able to grasp more concretely what can be understood by sustainable mobility.³⁶Mobility has complex consequences beyond transportation. For example, if certain journeys to state offices no longer have to be made in person, but can be done digitally from home, sustainable mobility can strengthen digital administration.

C. Sustainable Mobility—A Contradiction?

Following this brief overview of the terms sustainability and mobility, it will be outlined, just as briefly, what can be understood by sustainable mobility. First of all, it is striking that both components of the pair of terms represent a kind of renewal of well-known concepts: sustainability builds on the ideas of nature and environmental protection, and mobility derives from the notion of transportation.³⁷ Rammler, supra note 2, at 905.
However, unlike the individual terms, the combined concept of sustainable mobility is comparatively young, emerging only in the 1990s.³⁸Martin Held, Nachhaltige Mobilität, in Handbuch Verkehrspolitik 851 (Oliver Schöller, Weert Canzler & Andreas Knie eds., 2007) (who identified 858 “mentions in Google” as a reference for the popularization of this combination of terms).
Although the concept is still in its thirties, concerns about transportation’s impact on the environment long predate it.³⁹ Rammler, supra note 2, at 902; see also Radkau, supra note 5, at 181 (speaking of an “important nerve” in this regard).

It is therefore understandable that the concept of sustainable mobility had some growing pains. The guiding principle of sustainability is that satisfying the needs of the present should not make it impossible to satisfy the needs of future generations. Mobility, by contrast, involves the movement of people and goods, often associated with environmental costs, such as emissions that pollute the climate. This produces an inherent tension between sustainability and mobility. Stephan Rammler, Scientific Director of the Institute for Futures Studies and Technology Assessment at the Free University of Berlin in Germany, even asks “whether mobility and sustainability are possibly incompatible in principle”?⁴⁰Id. at 899.
While he ultimately answers this question in the negative, Rammler also offers an “optimistic” view: overcoming spatial constraints and achieving sustainability are compatible in principle, provided that the costs of mobility are reduced to such a level that the ecological basis is secured for future generations.

Thus, in order to be sustainable, mobility must not take place in ways that prevent future generations from meeting their needs. The means of transportation available in the future may not be exactly the same from those we have today. We do not, for example, necessarily have to save oil so that future generations can also drive combustion-powered cars. Alternatively powered vehicles can also meet the needs of future generations. One of the solutions to the tension between mobility and sustainability may lie in digitalization processes.⁴¹Id. at 900–901.
A simple example would be taking care of certain matters online instead of physically moving around. More broadly, however, sustainability may require a “needs-based mobility with less traffic.”⁴² Udo J. Becker, Was ist Nachhaltige Mobilität? 4 (2003), cited in Götz, supra note 26, at 331.

From a broader social science perspective, however, sustainable mobility can be understood as “the ecologically compatible and socially equitable design and guarantee of accessibility to facilities and communication access in a global society.”⁴³ Rammler, supra note 2, at 906–907.
To this end, regulatory and fiscal policy instruments play an important role. The social sciences provide a broad and differentiated toolbox of approaches that can be used in different combinations. Within the European framework, various political regulatory levels—from municipalities to the EU—are relevant and can promote supply-side innovations and demand-side behavioral changes. This includes, on the one hand, “product, usage and system innovations of the modes of transport” and, on the other hand, “planning instruments of an integrated settlement and location policy.”⁴⁴Id. at 906–907.
Within this broad framework, the social and economic pillars of sustainability can also be incorporated.

II. Sustainable Mobility in International, EU and National Austrian Law

A. Sustainable Mobility in International Law

Following the 1987 Brundtland Report, drafted by a prominent body of experts, sustainability came to be recognized as a central political goal of the United Nations.⁴⁵See World Commission, supra note 7, and the accompanying text.
The climate debate began to gain momentum, leading to the 1992 Rio De Janeiro Conference. It resulted in the signing of the Rio Declaration, which identified transport as a central need that could clearly be assigned to the pollutant-causing sector.⁴⁶ Rammler, supra note 2, at 903 (also drawing attention to the establishment of numerous research institutes in this context).
Additionally, the Declaration referenced “future generations,” and the need to dismantle or eliminate “unsustainable production methods and consumption habits.”⁴⁷Rio Declaration on Environment and Development, U.N. Doc. A/CONF.151/26 (Vol. I) (1992), princs. 3, 8.
While this development was of crucial importance for sustainability in international law, the link to sustainable mobility had not yet been clearly forged.⁴⁸However, road traffic is mentioned, for example, in the World Commission, supra note 7 (“Cities are filling with people, cars, and factories”). Forgotten today, this conference is also worth remembering because the then 12-year-old Severn Suzuki (now Cullis-Suzuki) gave a spectacular six-minute speech. Coming from Canada, she had traveled to Rio “to tell you elders, you must change your ways.” Listen to the Children – Severn Cullis-Suzuki’s famous speech on the environment (1992), YouTube (Oct. 27, 2017), https://www.youtube.com/watch?v=JGdS8ts63Ck.

As it turned out, it was not the UN but the Organisation for Economic Co-operation and Development (OECD), which offered the “first high point in the conceptualization” of sustainable mobility, through the organization of the 1996 Vancouver Conference “Towards Sustainable Transportation.”⁴⁹ Held, supra note 33, at 858; see also Towards Sustainable Transportation: the Vancouver Conference (OECD Proceedings, Mar. 24-27, 1996), https://rosap.ntl.bts.gov/view/dot/16010 [hereinafter OECD Report].
This was accompanied by a sobering realization that the transport systems in the OECD countries were not sustainable, and that the improvements in sustainability brought about by technological progress were being eaten up by the rapid increase in individual mobility and the transportation of goods.⁵⁰ Held, supra note 33, at 858 (citing OECD Report, supra note 51, at ¶ 56); see also infra note 108 and the accompanying text.
As if that were not enough, the forecast for future development was even gloomier.⁵¹ Held, supra note 33, at 858 (citing OECD Report, supra note 51, at ¶ 7). Similar results were also reached by two MIT studies, which were prepared in close consultation with representatives of large corporations from the private sector. See id. at 862.
Unfortunately, the predictions proved correct: today, transport is the most difficult sector to curb emissions.⁵²See infra note 83 and the accompanying text.

Following the 2002 World Summit on Sustainable Development in Johannesburg,⁵³See World Summit on Sustainable Development, 26 August-4 September 2002, Johannesburg, United Nations, https://www.un.org/en/conferences/environment/johannesburg2002 (last visited Dec. 9, 2025). The Conference resulted in the passing of the Johannesburg Declaration on Sustainable Development and several other documents.
and the 2012 United Nations Conference on Sustainable Development,⁵⁴The Conference resulted in the signing of The Future We Want: An Outcome Document. The UN’s vision included a provision on sustainable transport, proclaiming that “transportation and mobility are central to sustainable development,” they can “enhance economic growth and improve accessibility,” achieve a “better integration of the economy while respecting the environment.” Access to “environmentally sound, safe and affordable transportation” was recognized as bearing on important values and goals, such as “social equity, health, resilience of cities, urban-rural linkages and productivity of rural areas.” The UN expressed support for the development of sustainable transport systems, recognizing “the need to promote an integrated approach to policymaking at the national, regional and local levels,” and the “special development needs of landlocked and transit developing countries.” G.A. Res. 66/288, The Future We Want ¶¶ 132-133, U.N. Doc. A/RES/66/288 (Sept. 11, 2012), https://www.un.org/en/development/desa/population/migration/generalassembly/docs/globalcompact/A_RES_66_288.pdf.
the awareness of sustainable mobility increased, culminating in the UN’s Transforming Our World: 2030 Agenda for Sustainable Development, establishing a framework of sustainable development goals.⁵⁵G.A. Res. 70/1, Transforming Our World: The 2030 Agenda for Sustainable Development, U.N. Doc. A/RES/70/1 (Oct. 21, 2015), https://docs.un.org/en/A/RES/70/1.
The UN declared seeking to build “strong economic foundations for all our countries,” i.a., by adopting “policies which increase . . . sustainable transport systems.”⁵⁶Id. ¶ 27, at 8.
It explicitly referenced mobility in Goal 3.6, by 2030, the number of deaths and injuries from road traffic accidents worldwide should be halved, Goal 3.9, the number of deaths and illnesses from air, water, and soil pollution and contamination should be substantially reduced, and Goal 11.2, which seeks to “provide access to safe, affordable, accessible and sustainable transport systems for all, improving road safety, notably by expanding public transport, with special attention to the needs of those in vulnerable situations, women, children, persons with disabilities and older persons.”⁵⁷Id. at 16, 21.

Beyond the UN and OECD frameworks, the Alpine Convention—signed on November 7, 1991, by the environment ministers of the European Alpine countries—and its protocols, directly address sustainable mobility.⁵⁸Initially signed by Austria, France, Germany, Italy, Lichtenstein, Switzerland and the European Energy Commission, later expanded to Slovenia (1993) and Monaco (1994). The history of the Alpine Convention, https://www.alpconv.org/en/home/convention/history. Following the Council of the European Union decision, the EU has signed and concluded the Transport Protocol, implementing the Alpine Convention. See Council Decision 2007/799/EC, on the signature, on behalf of the Community, of the Protocol on the Implementation of the Alpine Convention in the field of transport (Transport Protocol), 2007 O.J. (L 323) 13; Protocol on the Implementation of the 1991 Alpine Convention in the Field of Transport (Transport Protocol), 2007 O.J. (L 323) 15. See also Werner Schroeder, Das Verkehrsprotokoll der Alpenkonvention – Anwendung und Durchsetzung im Recht der Europäischen Union, in Das Protokoll “Verkehr” der Alpenkonvention 17 (Josef Essl & Sebastian Schmid eds., 2019).
The Contracting Parties broadly committed themselves to a “comprehensive policy for the preservation and protection of the Alps [ . . . ] through the prudent and sustained use of resources.”⁵⁹Convention on the Protection of the Alps (Alpine Convention), Austrian Federal Law Gazette No. 477/1995, art. 2(1).
Under Article 2(2)(j), measures are to be taken to “reduce the volume and dangers of inter-Alpine and trans-Alpine traffic to a level which is not harmful to humans, animals and plants and their habitats.”

Within this framework, several protocols were adopted, with the Transport Protocol being particularly relevant for sustainable mobility. The contracting parties committed themselves to a “sustainable transport policy” in Article(1)(1).⁶⁰Protocol on the Implementation of the 1991 Alpine Convention in the field of Transport (“Transport” Protocol), Austrian Federal Law Gazette No. 234/2002. See Das Protokoll “Verkehr” der Alpenkonvention (Josef Essl & Sebastian Schmid eds., 2019).
In concrete terms, this means that this transport policy must:

(a) reduce the negative effects of and risks posed by intra-Alpine and transalpine transport to a level which is not harmful to people, flora and fauna and their environments and habitats, inter alia, by transferring an increasing amount of transport, especially freight transport, to the railways, in particular by creating appropriate infrastructures and incentives in line with market principles;

(b) contribute to the sustainable development of the habitats and economic areas in which people living in the Alpine region dwell and work by implementing a transport policy which encompasses all modes of transport and is harmonised between the various Contracting Parties;

(c) help to reduce and, as far as possible, avoid any impact which might endanger the role and natural resources of the Alpine region, the importance of which goes beyond the boundaries of the Alpine areas, and threaten its natural and cultural heritage;

(d) ensure the movement of intra-Alpine and transalpine transport at economically bearable costs by increasing the efficiency of transport systems and promoting modes of transport which are more environmentally-friendly and more economic in terms of natural resources;

(e) ensure fair competition between modes of transport.

Despite the existence of international and regional frameworks outlined above, sustainability in the global legal order primarily refers to sustainable development.⁶¹Cf. Ulrich Beyerlin, Sustainable Development, in Max Planck Encyclopedia of Public International Law (Oct. 2013), https://opil.ouplaw.com/display/10.1093/law:epil/9780199231690/law-9780199231690-e1609; Jane Hofbauer, Die Entwicklung des Sustainable Development Begriffs im Völkerrecht, 1 Zeitschrift für Nachhaltigkeitsrecht 53 (2021); International Law and Sustainable Development: Principles and Practice (Nico J. Schrijver & Friedl Weiss eds., 2004); Virginie Barral, Sustainable Development in International Law: Nature and Operation of an Evolutive Legal Norm, 23 Eur. J. Int. L. 377 (2012).
Sustainable mobility, by contrast, has fewer legal contours than its parent concepts of sustainability and mobility. International law, in this context, has acted more as a source of ideas and impetus, rather than providing comprehensive, legally binding guidelines. Recent developments, however, indicate a gradual shift.

In the Paris Agreement of 12 December 2015, 195 States committed to curbing climate change and making the global economy climate-friendly.⁶²Paris Agreement, Dec. 12, 2015, 3156 U.N.T.S. 79 (entered into force Nov. 4, 2016).
Naturally, this also includes mobility and transportation.⁶³Article 2 defines the main objectives of (1) limiting the increase in global average temperature, (2) reducing emissions and adapting to climate change, and (3) directing financial resources in line with climate change objectives.
In addition, the International Court of Justice (ICJ) has referred to international environmental concerns in its case law and, to a certain extent, has taken sustainability law into account by addressing the interests of future generations.⁶⁴See Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1996 I.C.J. Rep 226, ¶ 29, stating:

The Court also recognizes that the environment is not an abstraction but represents the living space, the quality of life and the very health of human beings, including generations unborn. The existence of the general obligation of States to ensure that activities within their jurisdiction and control respect the environment of other States or of areas beyond national control is now part of the corpus of international law relating to the environment.

See also GabCikovo-Nagymaros Project (Hungary/Slovakia), Judgment, 1997 I.C.J. Rep. 7, ¶ 140; Andreas Müller, Potenziale und Grenzen von Nachhaltigkeitsargumenten im Investitionsschutzrecht, in Nachhaltigkeit im Spiegel des Rechts 137 (Malte Kramme & Emanuel Ponholzer eds., 2023).
In its 2025 advisory opinion on climate change, the ICJ explicitly referenced intergenerational equity, stating that future generations should serve “as a guide for the interpretation of applicable rules.”⁶⁵Obligations of States in Respect of Climate Change, Advisory Opinion, 2025 I.C.J. Rep ¶ 157. Despite explicitly considering future generations, the Court also stated that “considerations of intergenerational equity must play a role infra legem, without displacing or exceeding the limits of the applicable law.” Id.
The European Court of Human Rights has gone even further in addressing the potential rights of future generations.⁶⁶Klimaseniorinnen v Switzerland, 2024 Eur. Ct. H.R. 304.
Similarly, the Inter-American Court of Human Rights, in its advisory opinion on climate change and human rights, affirmed that the human right to a healthy environment constitutes “a universal value that is owed to both present and future generations.”⁶⁷The Environment and Human Rights, Advisory Opinion OC-23/17, Inter-Am. Ct. H.R. 1, ¶ 59 (Nov. 15, 2017); see also Climate Emergency and Human Rights, Advisory Opinion OC-32/25, Inter-Am. Ct. H.R. (May 29, 2025), https://corteidh.or.cr/docs/opiniones/seriea_32_en.pdf.
However, neither court has yet addressed the more specific concept of sustainable mobility.

B. Sustainable Mobility in EU Law

The developments in international law inspired the goal of sustainable development in EU law.⁶⁸See Matthias Ruffert, Art. 3 TEU, in EUV/AEUV ¶ 23 (Christian Calliess & Matthias Ruffert eds., 6th ed. 2022).
Sustainable development is a designated objective of the EU in accordance with Article 3(3) of the Treaty of European Union (introduced by the 1997 Treaty of Amsterdam).⁶⁹The Treaty of Amsterdam already included a reference to sustainability, similar to the current provision:

[T]o promote, in the context of the achievement of the internal market and the strengthening of cohesion and environmental protection, the economic and social progress of their peoples, taking into account the principle of sustainable development, and to pursue policies which ensure that progress in economic integration is accompanied by parallel progress in other fields.

Treaty of Amsterdam amending the Treaty on European Union, the Treaties establishing the European Communities and certain related acts, 1997 O.J. (C 340) 1.
Under this provision, the EU “shall work for the sustainable development of Europe based on balanced economic growth and price stability, a highly competitive social market economy, aiming at full employment and social progress, and a high level of protection and improvement of the quality of the environment.”⁷⁰TEU, supra note 30, art. 3(3), 2012 O.J. C 326/13, at 17.
This internal market objective is complemented by the requirement of promotion of “solidarity between generations.”⁷¹Id.; see also Rudolf Geiger & Lando Kirchmair, Art. 3 TEU, in EUV/AEUV ¶ 8 (Rudolf Geiger, et al., eds., 7th ed. 2023) (explaining that inclusion of future generations is particularly relevant in connection with the objective of environmental protection).
Similarly, Article 11 of the Treaty on the Functioning of the European Union specifically links the integration of “environmental protection requirements . . . with a view to promoting of sustainable development.”⁷²See TFEU, supra note 30, art. 11, 2012 O.J. C 326/47, at 53.
Article 37 of the Charter of Fundamental Rights of the European Union reinforces this obligation, stating that a “high level of environmental protection and improvement of the quality of the environment must be integrated into the policies of the Union and ensured in accordance with the principle of sustainable development.”⁷³Charter, supra note 29, art. 37, 2012 O.J. C 326/391, at 403.

In 2001, the European Council adopted a sustainability strategy that added the environmental dimension to the “Lisbon Strategy” for growth and employment.⁷⁴Council of the European Union, Review of the EU Sustainable Development Strategy (EU SDS): Renewed Strategy, Doc. No. 10917/06 (June 26, 2006), https://register.consilium.europa.eu/doc/srv?l=EN&f=ST%252010917%25202006%2520INIT [hereinafter Lisbon Strategy] (discussing “Sustainable Transport” and recognizing the overarching goal “[t]o ensure that our transport systems meet society’s economic, social and environmental needs whilst minimizing their undesirable impacts on the economy, society and the environment.”). For a general overview, see Ursula Kopp, The EU SDS Process, ESDN Quarterly Report May 2006 (June 2006 update), https://www.esdn.eu/fileadmin/ESDN_Reports/2006-May-The_EU_SDS_process.pdf. For the early history of common transport policy in the European Community, including discussion of the 1992 White Paper on Sustainable Mobility, see Don C. Smith, The European Union’s Commitment to Sustainable Development: Is the Commitment Symbolic or Substantive in the Context of Transport Policy?, 13 Colo. J. Int’l Envtl. L. & Pol’y 241, 277 (2002).
Among other things, it addressed the way in which political decisions and course-setting can be aligned with the aspect of “sustainability.” In 2006, the updated version also identified sustainable transport as a key challenge for the first time.⁷⁵Lisbon Strategy, supra note 79.
This was followed by the Strategy for Sustainable and Intelligent Mobility of December 9, 2020, which includes reducing traffic-related emissions by 90 percent by 2050, spreading the use of zero-emission vehicles, ensuring healthy and sustainable mobility in and between cities, and implementing networked and automated multimodal mobility.⁷⁶Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions, Sustainable and Smart Mobility Strategy–Putting Europe’s transport on track for the future, COM (2020) 789 final (Sep. 12, 2020), https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=celex%3A52020DC0789.

As part of the so-called European Green Deal and the associated goal of becoming the first climate-neutral continent, the EU has declared the intention to emit no more net greenhouse gases by 2050. The interim target of reducing net greenhouse gas emissions by at least 55% by 2030 compared to 1990 can only be achieved by setting specific targets that also include transport policy in general and, in particular, the “development of sustainable and intelligent mobility and transport systems.”⁷⁷See Regulation (EU) 2021/1119 of the European Parliament and of the Council, recital 7, recital 26, recital 34, arts. 1, 2(2), 4(1), 2021 O.J. (L 243) 1 (EU) (“European Climate Law”) (Recital 34 provides for “the development of sustainable and smart mobility and transport systems”).

Accordingly, the “Fit for 55” mobility package was adopted, which bears the interim target of reducing emissions in the EU by at least 55% by 2030 in its name. This includes important initiatives to decarbonize road, air, and sea transport. To achieve the interim and final targets of 2030 and 2050, respectively, a comprehensive transformation of the transport sector is required, which must be accompanied by a 90% reduction in greenhouse gas emissions by 2050 compared to 1990 levels. This is because the transport sector has so far been one of the few sectors that have always had to record further increases in emissions instead of a reduction.

One measure to achieve this goal is the regulation to tighten CO₂ emission standards for new passenger cars and light commercial vehicles,⁷⁸Regulation (EU) 2023/851 of the European Parliament and of the Council, amending Regulation (EU) 2019/631 with respect to CO₂ emission standards for new passenger cars and light commercial vehicles, 2023 O.J. (L 110) 1.
which set a reduction target of 100% for passenger cars and light commercial vehicles from 2035 in 2023.⁷⁹The interim target, which would have had to be met by 2025, is now being amended to allow car manufacturers to exceed the CO₂ targets in one or two years if there is overcompensation in the following year(s). See Communication from the Commission, Industrial Action Plan for the European Automotive Sector, COM(2025) 95 final.
The regulation aims to reduce CO₂ emissions in road traffic in line with the EU’s climate targets. To this end, the emission reduction targets for 2030 (-45%) are to be raised and new targets set for 2035 (-65%) and 2040 (-90%). From 2035, 100% of all new passenger cars and light commercial vehicles must be emission-free.⁸⁰Originally, the regulation envisioned a reduction target of 100% by 2035. However, after significant pressure from car manufacturers and several EU member states, the European Commission introduced the “automotive package” in December 2025, which softens the emission target to 90%. Still, for the remaining 10%, there should be a compensation of these emissions by using low-carbon steel produced in the EU or by using sustainable fuels such as e-fuels and biofuels.
The situation is similar for heavy commercial vehicles.⁸¹Regulation (EU) 2024/1610 of the European Parliament and of the Council, amending Regulation (EU) 2019/1242 with respect to CO₂ emission standards for new heavy-duty vehicles, 2024 O.J. (L 1610) 1.
However, in December 2025, the European Commission introduced the “automotive package” following significant pressure from the automotive industry and certain member states. Among other things, the package softens the emission target for 2035. Rather than a 100% reduction target for newly registered vehicles, the goal was lowered to 90%. Yet, the remaining 10% of emissions must be offset by using low-carbon steel produced in the EU or sustainable fuels such as e-fuels and biofuels.⁸²For more information, see https://ec.europa.eu/commission/presscorner/detail/en/ip_25_3051.

Another measure is the Ordinance on the Development of Alternative Fuels Infrastructure, which came into force on 13 April 2024.⁸³Regulation (EU) 2023/1804 of the European Parliament and of the Council, on the deployment of alternative fuels infrastructure and repealing Directive 2014/94/EU, 2023 O.J. (L 234) 1, 1.
This is intended to increase the density of the charging network for electric vehicles and filling stations for alternative fuels in Europe and along the Trans-European Transport Networks.⁸⁴See also Matthias Zußner, Infrastruktur für neue Mobilitätsformen am Beispiel der E-Mobilität, in Mobilitätswende. Verkehre unter dem Einfluss von Nachhaltigkeit und Digitalisierung 71 (Arnold Autengruber & Arno Kahl eds., 2023) [hereinafter Mobilitätswende].

There is also the directive on the promotion of clean and energy-efficient road vehicles, which is intended to stimulate and promote the market.⁸⁵Directive 2009/33/EC of the European Parliament and of the Council, 2009 O.J. (L 120) 5, as amended by Directive (EU) 2019/1161 of the European Parliament and of the Council, 2019 O.J. (L 188) 116 (setting national minimum targets for the procurement of clean vehicles. The aim is to achieve a minimum proportion of clean vehicles in the total number of public authorities and certain public transport companies).
The EU Road Charges Directive (so-called Eurovignette Directive), whose original aim was to refinance infrastructure costs by levying charges on heavy goods vehicles, is now also intended to take external costs such as CO₂ emissions into account.⁸⁶Directive (EU) 2022/362 of the European Parliament and of the Council, 2022 O.J. (L 69) 1 (amending Directives 1999/62/EC, 1999/37/EC and (EU) 2019/520 regarding charging of vehicles for certain infrastructures).
Insofar as the proportion of cars with alternative driving systems is to be greatly increased in order to reduce emissions, the clean production of energy is also an important issue in terms of sustainable mobility. Accordingly, the directive to promote the use of energy from renewable sources, for example, is also relevant.⁸⁷Directive (EU) 2018/2001 of the European Parliament and of the Council, 2018 O.J. (L 328) 82. (on the promotion of the use of energy from renewable sources — recast).

In short, one could say that “mobility, transport and sustainability . . . are now inevitably interlinked, interwoven and have become indispensable for the functioning of today’s society.”⁸⁸Christoph Perathoner, Sustainable Legal Framework for Mobility of the European Union and the European Region Tyrol-South Tyrol-Trentino, in Nachhaltigkeit im Spiegel des Rechts 169 (Malte Kramme & Emanuel Ponholzer eds., 2023).
Unlike the international framework, which is characterized by a lack of concrete, actionable measures directly addressing sustainable mobility, the EU has regulated its specific facets.⁸⁹See supra Part II.A; see also Martin S. High, Sustainable Development: How Far Does U.S. Industry Have to Go to Meet World Guidelines?, 14 Alb. L.J. Sci. & Tech. 131, 143 (2003) (“One of the drawbacks of both the Rio Declaration and Agenda 21 is that they both fail to provide definite, concrete action items for the world governments, and therefore since the views of the agreements are so broad, they prove to be of limited practical use.”).
This is taken yet a step further in the domestic legislation of European states.

C. Sustainable Mobility in Austrian Law

Sustainability is enshrined at the highest level in the Austrian legal order. Section 1 of the Federal Constitutional Act on Sustainability stipulates that the Republic of Austria is committed to the principle of sustainability.⁹⁰Bundesverfassungsgesetz über die Nachhaltigkeit, den Tierschutz, den umfassenden Umweltschutz, die Sicherstellung der Wasser- und Lebensmittelversorgung und die Forschung [Federal Constitutional Act on Sustainability, Animal Welfare, Comprehensive Environmental Protection, Safeguarding the Water and Food Supply and Research], Austrian Federal Law Gazette I 111/2013, as amended by Austrian Federal Law Gazette I 82/2019 [hereinafter “Federal Constitutional Act on Sustainability”]. This Act has replaced the Federal Act on Comprehensive Environmental Protection, Austrian Federal Law Gazette 491/1984.
The goal is to ensure the best possible quality of life for future generations.⁹¹Id.
For the prevailing doctrine, this is a so-called state objective provision that has a benchmark function (but is not an individual right).⁹²See also Ferdinand Kerschner, Nachhaltigkeit in der Rechtswissenschaft – neue Teildisziplin oder nur ein Modethema? Ein kursorischer Abriss, in Nachhaltigkeit im Spiegel des Rechts 15, 19 (Malte Kramme & Emanuel Ponholzer eds., 2023), for whom: “Sustainable development . . . is ultimately an outgrowth, but also a requirement, of the fundamental right to freedom . . . The BVG sustainability flows into the not only permissible, but constitutionally required, dynamic interpretation of the fundamental right to freedom!” Id. See also Lando Kirchmair & Sebastian Krempelmeier, Das Klimaschutzprinzip im BVG Nachhaltigkeit: Ein schlafender Riese 31 Journal für Rechtspolitik 74 (2023).
In addition, Art. 13(2) Austrian Constitution stipulates that the federal, state, and local governments, must strive to ensure macroeconomic equilibrium and sustainability in their budget management. Budgetary management must be coordinated with regard to these objectives. Both constitutional provisions make general guiding decisions, without specific requirements being able to be derived from them according to the prevailing opinion. Nevertheless, they can have a strong effect.⁹³For a list of relevant provisions of state constitutional law, see Arnold Autengruber, Nachhaltigkeit bei der staatlichen Aufgabenbesorgung, in Nachhaltigkeit im Spiegel des Rechts 275 (Malte Kramme & Emanuel Ponholzer eds., 2023).

This influence is visible in numerous developments below the constitutional level that seek to implement the specified objectives.⁹⁴For example, the aforementioned Transport Protocol of the Alpine Convention is of importance in national law. See Eva Schulev-Steindl, Christoph Romirer & Lukas Liebenberger, Mobilitätswende: Klimaschutz im Verkehr auf dem rechtlichen Prüfstand, Teil 1, Recht der Umwelt 237 (2021); Eva Schulev-Steindl, Christoph Romirer & Lukas Liebenberger, Mobilitätswende: Klimaschutz im Verkehr auf dem rechtlichen Prüfstand, Teil 2, 1 Recht der Umwelt 5, 5-12 (2022); Dragana Damjanovic, Mobilitätswende: Die Rolle des Rechts beim Ausbau alternativer Mobilitätsdienstleistungen, in Festschrift für Eva Schulev-Steindl 65 (Daniel Ennöckl, Miriam Hofer & Verena Madner eds., 2024).
The most important example is the Mobility Master Plan 2030, a policy document of the Austrian government which outlines the new climate protection framework for the transport sector, and features the subtitle “sustainable–resilient–digital.” ⁹⁵Bundesministerium für Klimaschutz, Umwelt, Energie, Mobilität, Innovation und Technologie, Mobilitätsmasterplan 2030 für Österreich: Der neue Klimaschutz-Rahmen für den Verkehrssektor – Nachhaltig, resilient, digital (2021), https://www.bmk.gv.at/dam/jcr:6318aa6f-f02b-4eb0-9eb9-1ffabf369432/BMK_Mobilitaetsmasterplan2030_DE_UA.pdf [hereinafter “Mobility Master Plan 2030”].
The plan calls for a mobility transition combining transport transition and energy transition.⁹⁶Cf. Arnold Autengruber & Arno Kahl, Foreword, in Mobilitätswende, supra note 69, at xvi (discussing the Mobility Master Plan 2030); see also Schulev-Steindl, et al., supra note 76; Oliver Peck, Der rechtliche Rahmen für die Mobilitätswende, 1 Juridikum 102, 102-111 (2023); Theresa Tisch, Schaffung rechtlicher Rahmenbedingungen im Straßenplanungsrecht als Motor für die Mobilitätswende, 3 Juridikum 336, 336-344 (2023); Damjanovic, supra note 77.
It identifies cooperative, networked and automated mobility as having significant potential for reducing the negative climate and environmental impacts of transport—in both passenger and freight mobility—and indicates that realizing this potential requires “transparent, comprehensive and targeted control and steering by the public sector.” The plan also foresees a strong positioning of Austria in the international environment.⁹⁷See Mobility Master Plan 2030, supra note 78.
Another aspect is the regulation of standards for the infrastructure development of alternative fuels⁹⁸See Zußner, supra note 71, at 79 (citing BMVIT, et al., Nationaler Strategierahmen “Saubere Energie im Verkehr” 25 (2016), https://www.bmk.gv.at/themen/mobilitaet/alternative_verkehrskonzepte/elektromobilitaet/recht/saubere-energie.html).
and the implementation of the EU Directive on the promotion of the use of energy from renewable sources, e.g., by means of the Biomass Energy Sustainability Ordinance.⁹⁹Directive (EU) 2018/2001 of the European Parliament and of the Council, 2018 O.J. (L 328) 82; Biomasseenergie-Nachhaltigkeitsverordnung, BGBl. II Nr. 86/2023 (Austria) [Austrian Federal Law Gazette II 2023/86].

Although several further policy documents and statutory instruments embody the idea of sustainable mobility, there is still a lot of room for implementation of sustainable mobility at all relevant levels of the Austrian legal order.

Having surveyed international, EU, and domestic law’s progressive incorporation of sustainable mobility, Part III examines its practical implications and challenges, while Part IV moves to discuss specific examples and recommendations. The triple interconnected dimensions of sustainability provide a useful structure. The analysis begins with the ecological impacts of transport and mobility, to then turn to the economic incentives for the transition into sustainable mobility and their somewhat incipient application in European societies.

III. The Environmental Impact of Mobility and Financial Incentives for its Sustainability

A. Sustainable Mobility in Numbers

The movement of human biomass has increased approximately 40-fold since 1850 and now exceeds that of the entire animal world many times over.¹⁰⁰Yuval Rosenberg, et al., Human biomass movement exceeds the biomass movement of all land animals combined, 9 Nature Ecology 2259 (2025).
In the EU, the transport sector is responsible for around 25% of all greenhouse gas emissions. Within the transport sector, road traffic accounts for around 70% of all transport-related emissions. Cars alone cause around 60% of the CO₂ emissions of transport-related emissions.¹⁰¹European Environment Agency, Greenhouse gas emissions from transport in Europe, 31 Oct 2024, https://www.eea.europa.eu/en/analysis/indicators/greenhouse-gas-emissions-from-transport.
These numbers are similar in Austria, where around 30% of the greenhouse gas emissions come from the transport sector.¹⁰² Michael Anderl, et al., Climate Action Report 2021 124 (2021). Passenger transport is responsible for approximately 19 percent of GHG emissions, road freight transport for approximately 11 percent. See id. In addition to road traffic, “transport” also includes air traffic. However, national air traffic (take-off and landing within Austria) only contributes approximately 0.1 percent to Austria’s greenhouse gas emissions. See id. at 134.
According to the 2024 ministerial progress report, between 1990 and 2022, the transport sector recorded the highest increase of all sectors, with an emissions increase of 49.6%, mainly caused by the increase in road traffic.¹⁰³Fortschrittsbericht 2024 nach § 6 Klimaschutzgesetz 19 (2024) [Progress Report 2024 Pursuant to § 6 Climate Protection Act (KSG)], https://www.bmluk.gv.at/dam/jcr:5d3e9e51-c10a-45df-8c03-61e8a69ec63b/KSG_Fortschrittsbericht_2024.pdf.
In 2019, for example, the target value set by the Austrian Climate Protection Act¹⁰⁴See Anlage 2, Klimaschutzgesetz (KSG), BGBl. I Nr. 106/2011 (Austria) [Annex 2, Climate Protection Act, Austrian Federal Law Gazette I No. 106/2011].
was exceeded by more than 2 million tons of CO₂ equivalent.¹⁰⁵ Michael Anderl, et al., Climate Action Report 2021 72 (2021).
In the words of economist and social scientist Martin Held: “Sustainable mobility is the still recent history of becoming aware of the unsustainability of today’s prevailing transportation.”¹⁰⁶ Held, supra note 33, at 852, 867 (“Since the beginning of the discussion on sustainable mobility, the actual development has continued unabated in the direction of unsustainability, apart from certain individual aspects.”).

In order to achieve the goal of climate neutrality by 2040 in Austria (anchored in the 2020-2024 and the 2025–2029 government program of Austria and the Austrian Climate Protection Act) or the EU by 2050 (per the European Green Deal discussed above), intensive and far-reaching legal regulation is required, especially in the road transport sector. The massive reduction required to achieve climate neutrality is a long way off.¹⁰⁷See, e.g., Rammler, supra note 2, at 907 (“Rarely has the helplessness of transport experts been more tangible, even for non-expert observers, than during the 2011 International Transport Forum in Leipzig. In view of the central message of the ‘World Transport Outlook’ of the OECD’s International Transport Forum that the volume of traffic will triple worldwide by 2050, good advice was expensive.”).

B. A Wide Range of Financial Incentives to Promote Sustainable Mobility.

In principle, there are numerous different ways in which the law can encourage desired behavior among citizens. When it comes to sustainable mobility, many if not all roads lead to Rome. On the one hand, it may be desirable to prevent certain journeys altogether, or to provide incentives to avoid them. If this is not possible, a further goal may be to make the necessary journeys in an environmentally friendly way, i.e., without causing emissions. This might not always be very likely to happen either. Therefore, there is still the option of improving efficiency by at least reducing emissions.¹⁰⁸See also Mobility Master Plan 2030, supra note 78, at 20-26, 26036, 36-46 (discussing the triad “Avoid without sacrifice,” “Shift where possible” and “Improve and design efficiently”).

An important way to steer human mobility to produce less emissions are financial incentives.¹⁰⁹ Rammler, supra note 2, at 906-7 (speaking of “a broad and versatile toolkit of approaches that can be applied in various combinations at different levels of political regulation, from the local to the EU level, to promote supply-side innovations and demand-side behavioral changes.”). All incentives mentioned should be in accordance with the law. For example, this includes international law and WTO rules, which ensure non-discrimination.
These incentives can be differentiated according to the target audience. They can be used on both the demand side—influencing the behavior of individuals and companies—and the supply side—supporting providers of sustainable transport services. In the multi-level system of the EU, incentives can target individuals, companies, and states differently, depending on the needs. In addition, sectorial distinctions can be made to address the differentiated impact on sustainable mobility, including roads, rail, air, and water sectors. Lastly, the digital sector should not be neglected either as it can play a major role in avoiding travel.

Thus, a general taxonomy of incentives is important in order to be able to accurately answer the question of which measures are appropriate in each case and how the desired behavior can best be achieved. Broadly speaking, financial incentives can be positive in nature, such as subsidies tax or fee reductions. Others can be negative, in the form of higher or additional taxes, fees and, in certain cases, even penalties.

That said, in the area of sustainable mobility, the following positive financial incentives for individuals are conceivable in general:

a) Subsidies: e.g., for the purchase or operation of less environmentally harmful vehicles; for more environmentally friendly collective use of vehicles, for public transportation.¹¹⁰See, e.g., Jonatan J. Gómez Vilchez & Christian Thiel, The Effect of Reducing Electric Car Purchase Incentives in the European Union, 10(4) World Electr. Veh. J. 64 (2019) (examining the role of subsidies in incentivizing electric car adoption); Gregory H. Shill, Should Law Subsidize Driving?, 95 N.Y.U L. Rev. 498 (2020).

b) Tax reliefs: e.g., reduced income tax or value-added tax on the purchase or operation of less environmentally harmful vehicles or their collective use.¹¹¹See, e.g., Sergio Luis Náñez Alonso, The Tax Incentives in the IVTM and “Eco-Friendly Cars”: The Spanish Case, 12 Sustainability 3398 (2020); Georgina Santos & Huw Davies, Incentives for Quick Penetration of Electric Vehicles in Five European Countries: Perceptions from Experts and Stakeholders, 137 Transp. Res. Part A: Pol’y & Prac. 326 (2019).

c) Fee reductions: e.g., free or cheaper parking spaces for such vehicles.

For companies and providers, the incentives are sometimes different. Positive incentives could be:

a) Subsidies: e.g., for fleet conversions to less environmentally harmful vehicles; charging infrastructure.

b) Tax reliefs: reduced taxes for less environmentally harmful fleets.¹¹²See, e.g., Alexandros Dimitropoulos, et al., Not Fully Charged: Welfare Effects of Tax Incentives for Employer-Provided Electric Cars, 78 J. Envtl. Econ. & Mgmt. 1 (2016).

c) Fee reductions: e.g., lower registration fees, toll exemptions.¹¹³See EU backs extended toll exemption for zero emission trucks, European Alternative Fuels Observatory (Oct. 10, 2025), https://alternative-fuels-observatory.ec.europa.eu/general-information/news/eu-backs-extended-toll-exemption-zero-emission-trucks; see also Adam Davis, et al., Assessing the Potential Impacts of Toll Discounts on Zero-Emission Vehicle Adoption (National Center for Sustainable Transportation Rep., Jan. 2023), https://doi.org/10.7922/G26T0JZM.

Negative incentives include the following:

a) Higher taxes: e.g., higher annual tax for environmentally harmful vehicles or their operation; removal of tax breaks for environmentally harmful vehicles or their operation.

b) Higher fees: Fees for driving environmentally harmful vehicles in certain zones; fees for parking environmentally harmful vehicles.

c) Penalties: e.g., low emission zones (LEZs) in conjunction with fines for environmentally harmful vehicles.¹¹⁴See, e.g., Maira Delgado-Lindeman, et al., Characteristics and Effects of Low Emission Zones in Europe: A Systematic Literature Review, 17 Eur. Transp. Res. Rev. 54 (2025); Sebastiaan Deuten, et al., Analysis and testing of electric car incentive scenarios in the Netherlands and Norway, 151 Technological Forecasting and Social Change 119847 (2020) (analyzing the use of different incentives, including penalties, in Norway and Netherlands); Gregory H. Shill, Beyond Congestion Pricing, 2025 J. L. Mob. 1 (examining congestion pricing in New York); Jonn Axsen & Michael Wolinetz, Taxes, tolls and ZEV zones for climate: Synthesizing insights on effectiveness, efficiency, equity, acceptability and implementation, 156 Energy Policy 112457 (2021).

Finally, one can consider mixed or innovative mechanisms, such as the following:

a) Tradable credits: e.g., the EU Emissions Trading System (EU ETS), a market-based system that uses the “cap and trade” model to reduce greenhouse gas emissions, including the planned EU ETS 2, which will include carbon emissions from road transport.¹¹⁵See About the EU ETS, https://climate.ec.europa.eu/eu-action/carbon-markets/about-eu-ets_en (last visited Dec. 9, 2025); see also Wil Burns, The European Union’s Emissions Trading System: Climate Policymaking Model, or Muddle? (Part 1), 30 Tul. Envtl. L.J. 189 (2017); The European Union’s Emissions Trading System: Climate Policymaking Model, or Muddle? (Part 2), 31 Tul. Envtl. L.J. 51 (2017).

b) Pay-as-you-drive insurance: financial rewards for lower mileage or eco-friendly driving.¹¹⁶See, e.g., Jan Willem Bolderdijk & Linda Steh, Pay-as-You-Drive Vehicle Insurance as a Tool to Reduce Crash Risk: Results so Far and Further Potential, Int’l Transp. F. Discussion Paper No. 2011/23 (OECD 2011), https://www.oecd.org/content/dam/oecd/en/publications/reports/2011/10/pay-as-you-drive-vehicle-insurance-as-a-tool-to-reduce-crash-risk_g17a2054/5kg29s5cp90w-en.pdf.

c) Mobility-as-a-Service (MaaS) packages: Financial discounts for integrated sustainable mobility (public transport, bicycles, or car sharing).¹¹⁷See, e.g., Benjamin Maas, Literature Review of Mobility as a Service, 14 Sustainability 8962 (2022).

d) Cash out programs: e.g., employees receiving money if they do not use company parking spaces (redirecting funds toward sustainable commuting).¹¹⁸See, e.g., Stefan Tscharaktschiew & Felix Reimann, On employer-paid parking and parking (cash-out) policy: A formal synthesis of different perspectives, 110 Transport Policy 499 (2021).

C. How Can We Determine Which Measures are Effective?

Considering all the aforementioned measures, there are numerous and very different financial ways to promote sustainable mobility or, to put it differently, make unsustainable mobility unattractive. Yet, it is important to distinguish the effects of these different categories. For example, the analysis of different tax incentives for air travel (e.g., kerosene tax) will differ from that for road transport, even though both involve the taxation of propellant fuel (e.g., kerosene or diesel tax). If subsidies or fees are added, the picture becomes even more complicated.¹¹⁹For an analysis of climate protection regulation in relation to air traffic, see, e.g., Jörgen Larsson, et al., International and National Climate Policies for Aviation: A Review, 19 Climate Pol’y 787 (2019); Stef Proost, Looking for Winning Policies to Address the Climate Issue in EU Aviation, 115 J. Air Transport Mgmt. 102534 (2024).
In order to understand which incentives are particularly effective and which are comparatively less successful, it is important to learn from disciplines other than law.

A recent study examining financial incentives for electric vehicles in Europe, for example, has produced interesting conclusions.¹²⁰See, e.g., Edlaine Correia Sinézio Martins, Julien Lépine & Jacqueline Corbett, Assessing the Effectiveness of Financial Incentives on Electric Vehicle Adoption in Europe: Multi-Period Difference-in-Difference Approach, 189 Transp. Res. Part A: Pol’y & Prac. 104217 (2024) (comparing data from 30 countries (including Austria) for the period 2012 to 2021).
Purchase incentives, on the one hand, are associated with an increase in registrations of electric vehicles, and this effect appears to persist over time. Incentives for ownership, on the other hand, do not contribute to an increase in registrations of electric vehicles. The effect of the measures varies between countries with different gross domestic product per capita as well as different consumption of renewable energies, underscoring the need for closer, country-specific analysis.¹²¹See, e.g., with a focus on Austria, Viktoria Gass, Johannes Schmidt & Erwin Schmid, Analysis of Alternative Policy Instruments to Promote Electric Vehicles in Austria, 61 Renewable Energy 96 (2014) (concluding that an effective tax increase would not be politically feasible because it would have to be too high to be successful, and that a purchase subsidy would be efficient). See also Maximilian Kloess & Andreas Müller, Simulating the Impact of Policy, Energy Prices and Technological Progress on the Passenger Car Fleet in Austria—A Model-Based Analysis 2010–2050, 39 Energy Pol’y 5045 (2011) (arguing that, based on their simulation, significant savings in energy consumption and greenhouse gas emissions can be achieved through political framework conditions for passenger cars, and that appropriate taxation of fuels and motor vehicles could promote efficient drive technologies and low-carbon fuels). For a comparative note considering Germany, Austria, and Switzerland from a tax law perspective, see Philipp Lust, New Federal Government—Is There a New Approach to Politics and Budgeting? A Contribution to the Discussion and Reflection on Certain Political Habits, 65 Pub. Fin. In Austria 187, 197 n.21 (2024).
At the same time, this study’s results suggest that a major cost advantage of electric vehicles, namely in operation—lower maintenance and energy costs—may function similarly to incentives and could have less of an impact on consumers’ purchasing decisions.¹²²See, e.g., Gass, et al., supra note 94, at 99 (and sources cited therein).

D. European Examples of Financial Incentives for Sustainable Road Transport

Norway has long been known for its widespread use of electric vehicles. This is linked to incentives such as exempting electric vehicles from vehicle registration tax and reducing toll charges. There are also negative incentives, such as taxes on fossil fuels. An empirical study showed that the exemption from vehicle registration tax for electric vehicles, in particular, has had a major impact. Without this incentive, electric vehicles would only have had a 25 % market share in Norway in 2021, instead of 66 %. This, in turn, would have increased CO₂ emissions accountable to new cars by 167 %.¹²³Costanza Cincotta & Øyvind Thomassen, Evaluating Norway’s Electric Vehicle Incentives, 146 Energy Econ. 108490 (2025).

In France, the Forfait Mobilités Durables [Sustainable Mobility Allowance], the flat rate for sustainable mobility is also another positive incentive that makes alternatives to road transport more attractive. This program, which replaced the mileage allowance for bicycles, among other things, enables employers to provide financial support to employees for environmentally friendly commuting.¹²⁴See Arnaud Passalacqua, et al., Encadrer les Déplacements Carbonés Liés au Travail: Une Politique Publique à Imaginer 19 (2024), https://hal.science/hal-05069875v1; see also Daniel B. Rodriguez & Nadav Shoked, Comparative Local Government Law in Motion: How Different Local Government Law Regimes Affect Global Cities’ Bike Share Plans, 42 Fordham Urb. L.J. 123 (2014) (providing a typology of bike share plans).
In the Netherlands, too, the possibility of tax-free commuting by bicycle, a bicycle leasing system, and the fietsplan [Bicycle Plan] program, which allows the purchase price of a bicycle to be deducted from taxes every three years, provide financial incentives that make alternatives to road transport more attractive.¹²⁵See I.M. Wienk, Assessing Financial Schemes for Commuter Cycling: A Comprehensive Social Cost-Benefit Analysis (2023) (Master’s thesis, TU Delft), https://repository.tudelft.nl/record/uuid:52f0192e-ab29-470d-9093-88c7ae8ee565.

Similar was the intention behind the so-called Deutschland-Ticket [Germany ticket], to make the use of regional trains and public transport systems more attractive by offering a relatively inexpensive and uniform ticket.¹²⁶See Andreas Krämer, Das Deutschlandticket in einer Wohlfahrtsökonomischen Betrachtung, 76(3) Internationales Verkehrswesen 38 (2024).
Although not directly comparable due to its size, Luxembourg has gone a step further by making local and regional public transport free of charge since 2020.¹²⁷See Wojciech Kębłowski, et al., Fare-Free Public Transport: From Policy Fringes to an Established Practice, in The Routledge Handbook of Sustainable Urban Transport 257, 257 (Lucy Budd, Stephen Ison & Maria Attard eds., 2025) (noting that evidence is limited for a significant shift from private motorized transport to public transport, but that social sustainability could be strengthened through reduced transport poverty and social inequalities).

E. Financial Incentives to Promote Sustainability in Austrian Road Transport

Several tax instruments are currently relevant to vehicle cost in Austria, three of which are particularly significant. First, the Normverbrauchsabgabe (NoVA) [Standard Consumption Tax] is levied as a percentage of the purchase price and calculated on the basis of the vehicle’s standardized fossil fuel consumption.¹²⁸See Paul Eckerstorfer & Markus Riegler, Fiskalische und ökologische Auswirkungen der NoVA-Reform 2020, [Fiscal and Ecological Effects of the NoVA Reform 2020], 62 Pub. Fin. In Austria 33 (2021).
A bonus-malus system is applied with regard to a vehicle’s CO₂ emissions. For vehicles with CO₂ emissions above the threshold of 160 g/km, an additional amount of EUR 25/g must be paid. Since electric vehicles do not emit any CO₂ during operation, they are not affected by NOVA.¹²⁹See Normverbrauchsabgabegesetz (NoVAG 1991) § 3(1) (1), BGBl. Nr. 695/1991 (Austria) [§ 3(1) (1) of the Standard Consumption Tax Act – NoVAG 1991, Austrian Federal Law Gazette No. 695/1991].
Since July 1, 2025, light commercial vehicles (N1) have once again been exempt from NOVA. This means that (small) vans will tend to be cheaper to purchase than lighter and more fuel-efficient passenger cars. The reasoning behind this was to promote businesses. In addition, the CO₂ deduction amount will decrease by 3 g/km in 2025 and each subsequent year.¹³⁰Section 6 (2) NoVAG 1991 specifies the formula for passenger cars using the CO₂ emission value, which is a combined WLTP value in g/km. The WLTP value is a standardized test procedure (written out as Worldwide Harmonized Light-Duty Vehicles Test Procedure), which measures the fuel consumption, CO₂ emissions, and other emission values of light-duty vehicles worldwide in a realistic manner. 112 (CO₂ deduction amount) g/km is subtracted from the CO₂ emission value in g/km and the amount is divided by five. The maximum tax rate is 50%. If a vehicle has CO₂ emissions higher than 200 g/km (penalty threshold), the tax for CO₂ emissions exceeding the penalty threshold increases by 50 euros (penalty amount) per g/km. The tax calculated in this way is reduced by a deduction of 350 euros (deduction amount).
This will increase the NOVA for most vehicles. The penalty threshold will also be lowered by 15 g/km each year, the amount will increase by EUR 10 annually, and the maximum tax rate will be raised by 10 %. In addition, consumers will have to pay 20 % VAT on the total purchase price, including fuel consumption tax, as is the case with many other products.

Second, the engine-related vehicle tax (motorbezogene KFZ-Steuer) is tied to the engine power, and must be paid for each month that an insurance contract is in force. On April 1, 2025, the complete exemption from motor-related insurance tax for electric cars was abolished and replaced by moderate taxation, which amounts to only a fraction of the tax for comparable vehicles with combustion engines.¹³¹Budgetsanierungsmaßnahmengesetz 2025, BGBl. I Nr. 7/2025 (Austria) [Budget Consolidation Measures Act, Austrian Federal Law Gazette I No. 7/2025].
The weight of the vehicles is taken into account, reflecting the original idea of a road usage tax and the subsequent environmental tax. At the same time, excessively heavy and powerful electric vehicles will be taxed slightly more heavily than compact small cars. In addition, consumers must pay 11 % insurance tax on the motor-related tax.

Third, vehicles with combustion engines are subject to a Mineral Oil Tax (Mineralölsteuer or MöST), which currently amounts to EUR 0.447/l for gasoline vehicles and EUR 0.347/l for diesel vehicles (the so-called diesel privilege). As with the purchase of a vehicle, 20 % VAT is added to the price of diesel or gasoline.

Low-emission electric vehicles thus remain outside of NoVA and MöST, though they are affected by the engine-related insurance tax. The effectiveness of this regulation for the goal of achieving sustainable mobility or rather the question whether this is helpful for achieving a more sustainable mobility, can be understood based on empirical studies suggesting a stronger steering effect on purchasing decisions.¹³²See supra Part III.C-D.
Yet, policymakers remain reluctant to introduce certain negative tax incentives—such as the abolition of the diesel privilege—in order to make mobility more sustainable, even though such a reform could directly target emissions by tying the tax burden to consumption.¹³³See also Lust, supra note 121, at 197 n.21 (noting that such taxes would be “a simple and direct indicator of the extent of actual CO2 emissions” and could “directly and realistically motivate people to drive fuel-efficient vehicles and use them moderately.”).

In addition, there are EU directives, for instance on the promotion of clean and energy-efficient road vehicles, which is intended to stimulate and promote the market.¹³⁴Directive (EC) 2009/33 of the European Parliament and of the Council, 2009 O.J. (L 120) 5, as amended by Directive (EU) 2019/1161 of the European Parliament and of the Council, 2019 O.J. (L 188) 116, which sets national minimum targets for the procurement of clean vehicles. The aim is to achieve a minimum proportion of clean vehicles in the total number of public authorities and certain public transport operators.
The EU Infrastructure Costs Directive (“Eurovignette”), whose original aim was to refinance infrastructure costs by levying charges on heavy goods vehicles, is now also intended to take external costs such as CO₂ emissions into account.¹³⁵Directive (EU) 2022/362 of the European Parliament and of the Council, 2022 O.J. (L 69) 1, amending Directives (EC) 1999/62, 1999/37, and (EU) 2019/520, with regard to the levying of charges for the use of certain transport routes by vehicles.

Taking all of this into account, one might ask if combustion engine vehicles–or even low-emission electric vehicles–represent the future of mobility. The intuitive answer comes easily to mind. In Part IV, the discussion will therefore turn to the (near) future: the role of fully electric, self-driving or autonomous cars, in sustainable mobility, and the regulatory and policy their deployment will raise.

IV. Sustainable Mobility Using the Example of Self-Driving Cars

As examined in Parts I and II, sustainability regulations, particularly those concerning mobility, require transportation systems to be designed so that future generations are not disproportionately affected in their ability to meet their needs. This entails regulating present mobility needs and related natural resource consumption in a way that preserves future generations’ quality of life. Self-driving cars are increasingly popular, and are a rapidly advancing technology set to massively change traffic, the streetscape, and the everyday life of almost everyone. In December 2021, the Federal Motor Transport Authority in Germany granted the world’s first type approval for an automatic lane keeping system,¹³⁶Press Release No. 49/2021, German Federal Motor Transport Authority, https://www.kba.de/SharedDocs/Downloads/DE/Pressemitteilungen/2021/pm_49_2021_erste_Genehmigung_automatisiertes_Fahren.pdf?__blob=publicationFile&v=2.
following the enactment of a new law on autonomous driving.¹³⁷In Germany, Section 1a was added to the Road Traffic Act (Straßenverkehrsgesetz or StVG) in 2017. This makes the “operation of a motor vehicle by means of a highly or fully automated driving function . . . permissible if the function is used as intended.” In July 2021, the law on autonomous driving came into force with which the StVG was again amended accordingly. Gesetz zur Änderung des Straßenverkehrsgesetzes, BGBl I 2021, 3089, 3108 (Ger.); see also Lando Kirchmair, How to Regulate Moral Dilemmas Involving Self-Driving Cars: The 2021 German Act on Autonomous Driving, the Trolley Problem, and the Search for a Role Model, 24 German L. J. 1184, 1186, 1198-99 (2023) (examining the German legislation).
This proactive regulatory approach is a welcome change, since historically, both Germany and Austria lagged behind other jurisdictions in designing environmentally conscious transport policy.¹³⁸For example, catalytic converters were only introduced in Germany and Austria towards the end of the 1980s, a good 10 years later than in the USA or Japan, where stricter regulations to curb car emissions were already in place earlier. Rammler, supra note 2, at 903.

The regulation of self-driving vehicles offers a compelling case study of sustainable mobility policies. Incorporating sustainability concerns in the development and operation of these vehicles has the potential to significantly enhance the sustainability of mobility. Self-driving cars are often advertised with great promises of improved safety and environmental friendliness.¹³⁹In this regard, see the British consultation on protecting the use of certain terms in self-driving vehicles marketing. Automated vehicles: protecting marketing terms (June 10, 2025), https://www.gov.uk/government/consultations/automated-vehicles-protecting-marketing-terms.
While there may be some truth in these claims, it would be erroneous to assume that such pledges are guaranteed to materialize.

The safety claim depends, first, on the maturity of the technology, and second, on the resolution of novel ethical dilemmas.¹⁴⁰See Norbert Paulo & Lando Kirchmair, Moral Dilemmas Involving Self-Driving Cars: How to Regulate Them and Why Your Opinion Matters (2024).
The good-for-the-environment claim may also be true in principle, but is anything but a foregone conclusion. As early as 1865, William Stanley Jevons pointed out that more efficient steam engines would not conserve Britain’s coal reserves. On the contrary, he predicted that an improved steam engine would increase the demand for these machines overall, which would ultimately lead to an increased demand for coal.¹⁴¹See Peter Norton, Autonomous Vehicles: A Powerful Tool if You Can Get the Problem Right, Robohub (2014), https://www.govtech.com/transportation/autonomous-vehicles-powerful-tool-if-you-can-get-the-problem-right.html (citing William S. Jevons, The Coal Question. An Inquiry Concerning the Progress of the Nation, and the Probable Exhaustion of Our Coal-Mines (1865)). The German sociologist Hartmut Rosa has identified a similar phenomenon when he states that the invention of email has not led to us gaining time because an email is written faster than a letter. On the contrary, he argues that the acceleration of modernity has led to us writing so many more emails than we used to write letters that the time saved by technological progress has, to a certain extent, been reversed. Most people are familiar with the daily phenomenon of receiving a flood of emails and writing quite a few of them. At least much more than letters used to be written. See Hartmut Rosa, Beschleunigung. Die Veränderung der Zeitstrukturen in der Moderne (2005); Dieter Schnaas & Christopher Schwarz,”Die eingesparte Zeit ist im Eimer,” WirtschaftsWoche (Jan. 1, 2014) (interviewing Rosa).
The thesis of the American technology historian Peter Norton picks up on these paradoxes and also sees the danger that we could suffer a similar fate with self-driving cars.

Assuming for the sake of the argument that self-driving cars will be safer, more economical, and require much less attention from the driver, such gains would be a spectacular achievement, but only if the total mileage (km per person) remained constant. That is unlikely. Rather, increased safety, added comfort, and lower threshold for using such vehicles, will probably lead to a sharp increase in their overall demand.¹⁴²Peter Norton, Autonomous Vehicles: A Powerful Tool if You Can Get the Problem Right, Robohub (2014), https://www.govtech.com/transportation/autonomous-vehicles-powerful-tool-if-you-can-get-the-problem-right.html; see also Peter Norton, Autonorama. The Illusory Promise of High-Tech Driving (2021).
Thus, self-driving cars are not automatically more environmentally friendly or sustainable, and the regulatory framework governing self-driving vehicles is of paramount importance.¹⁴³See also Sven O. Hansson, Matts-Åke Belin & Björn Lundgren, Self-Driving Vehicles-an Ethical Overview, 34 Philosophy & Technology 1383, 1396 (2021).
Without appropriate regulation, there is a risk that many journeys without passengers will be accepted in exchange for increased comfort, or that other forms of transportation will be discriminated against.¹⁴⁴See Peter Norton, Autonomous Vehicles: A Powerful Tool if You Can Get the Problem Right, Robohub (2014), https://www.govtech.com/transportation/autonomous-vehicles-powerful-tool-if-you-can-get-the-problem-right.html (“If we rebuild the landscape for autonomous vehicles we may make it unsuitable for anything else – including walking. What kind of city do we want – and what kind of mobility will serve it best?”).

A particularly useful approach is the “three-pronged” sustainability framework.¹⁴⁵See Joseph Huber, Towards industrial ecology: sustainable development as a concept of ecological modernization, 2 J. Environ. Policy Plan. 269 (2000); particularly focusing on efficiency, see also Ernst Ulrich von Weizsäcker, Amory B. Lovins, and L. H. Lovins, Faktor Vier. Doppelter Wohlstand – halbierter Naturverbrauch (1995); for an overview, see Marco Rudolf & Mario Schmidt, Efficiency, sufficiency and consistency in sustainable development: Reassessing strategies for reaching overarching goals, 227 Ecological Economics 108426 (2025); for the German speaking scholarship see, Oliver Schwedes, Verkehrspolitik. An Interdisciplinary Introduction 14-15 (2nd ed 2018).
This approach is characterized by a balanced, cohesive integration of three key principles: efficiency, consistency, and sufficiency. Exclusive reliance on efficiency-based strategies, for example, risks producing medium- and long-term effects of overcompensation of ecologically sensible savings.¹⁴⁶Id. at 906-907.
Such dynamics can, and should, be prevented through early, targeted regulatory intervention.

Smart regulation of technical innovations such as self-driving cars is therefore essential. For instance, the implementation of specific regulations on self-driving vehicles could potentially incentivize their utilization as a mode of mass transportation, while concurrently disenfranchising individual transportation. In the context of high traffic volume, it would be advantageous for passengers to travel together on routes with high passenger volume, as opposed to traveling individually. In addition, optimization concepts usually result in higher demand due to the increase in efficiency. Experts speak of the so-called “rebound effect,” which refers to the fact that emissions saved by increasing efficiency are overcompensated for by increased demand.¹⁴⁷See Jasmin Möller, et al., Sustainable City Logistics: Rebound Effects from Self-Driving Vehicles, in Digital Transformation in Maritime and City Logistics (Carlos Jahn, et al., eds., 2019), https://www.econstor.eu/bitstream/10419/209397/1/hicl-2019-28-299.pdf.

A. The Regulation of Self-Driving Cars in the United Nations

The regulation of motor vehicles is rooted, in part, in the 1958 Agreement administered within the United Nations framework.¹⁴⁸Agreement Concerning the Adoption of Uniform Technical Prescriptions for Wheeled Vehicles, Equipment and Parts Which Can Be Fitted and/or Be Used on Wheeled Vehicles and the Conditions for Reciprocal Recognition of Approvals Granted on the Basis of These Prescriptions, E/ECE/TRANS/505/Rev.2 (UNECE Dec. 20, 1958), https://treaties.un.org/pages/viewdetails.aspx?src=ind&mtdsg_no=xi-b-16&chapter=11&clang=_en. Since the amendment in 1995, non-European states have also been allowed to accede to the agreement and the rules adopted by the forum are now referred to as UN rules. Currently, E/ECE/TRANS/505/Rev.3 is in force.
The Agreement—together with the numerous rules adopted in this context by the World Forum for Harmonization of Vehicle Regulations—constitutes a central tool for uniformly regulating fundamental aspects of vehicle construction.¹⁴⁹The World Forum for Harmonization of Vehicle Regulations is a working group of the Inland Transport Committee of the United Nations Economic Commission for Europe with the task of creating uniform regulations for vehicle construction. It was founded on June 6, 1952, as the “Working Group on Vehicle Construction.” See Vehicle Regulations: Introduction, UNECE, https://unece.org/wp29-introduction.
The Forum deals with vehicle safety and environmental protection regulations, among other things. On June 24, 2020, it issued the first binding international rules for self-driving cars at “Level 3,” on setting the standard for all parties to this Agreement.¹⁵⁰UN Regulation No. 157, Uniform Provisions Concerning the Approval of Vehicles with Regard to Automated Lane Keeping Systems, E/ECE/TRANS/505/Rev.2 (entered into force Jan. 22, 2021), https://treaties.un.org/pages/ViewDetails.aspx?src=TREATY&mtdsg_no=XI-B-16-157&chapter=11&clang=_en.

Additionally, the self-driving cars amendment to UN Regulation No. 157 was adopted on 22 June 2022.¹⁵¹Proposal for the 01 Series of Amendments to UN Regulation No. 157 (Automated Lane Keeping Systems), Economic Comm’n for Europe, Inland Transp. Comm., ECE/TRANS/WP.29/2022/59/Rev.1 (2022), https://unece.org/sites/default/files/2025-03/ECE_TRANS_WP.29_2022_59_Rev.1e.pdf.
It entered into force in January 2023 for those contracting states that have opted to apply it. It extended the maximum speed limit for automated driving systems for passenger cars and light commercial vehicles to 130 km/h on freeways and enabled automated lane changing.

Lastly, the World Forum for Harmonization of Vehicle Regulations also deals with environmental protection—through the Working Party on Pollution and Energy—and has issued general regulations in this area, so far there have not been passed any rules specifically addressing environmental issues relating to self-driving cars.¹⁵²See Working Party on Pollution and Energy, UNECE, https://unece.org/transport/vehicle-regulations/working-party-pollution-and-energy-introduction (last visited Dec. 10, 2025).

B. The Regulation of Self-Driving Cars in the European Union

The EU sees connected and automated mobility as an opportunity and has therefore set itself the goal of regulating self-driving cars at an early stage to enable their use on Europe’s roads. This is not only relevant for road safety and improved mobility options, but also opens up the opportunity to promote car-sharing systems and mobility-as-a-service (i.e., the sale of journeys instead of vehicles), and also to accelerate the electrification of vehicles and electromobility.¹⁵³ European Commission, Towards Automated Mobility: An EU Strategy for the Mobility of the Future 283 (2018).
This is an approach that fundamentally takes into account the requirements of sustainable mobility in the chosen example of self-driving cars. However, the European Commission has explicitly stated that we should not expect that the problems of congested roads, traffic emissions and accident fatalities will be solved by technological changes alone: “We need to manage properly the long transition phase and make sure future vehicles are embedded in a transport system that favors social inclusion, low emissions and overall efficiency.”¹⁵⁴Id.

This raises the question of whether and, if so, how this is reflected in the regulation of this new technology. First of all, the EU’s type approval regulation for motor vehicles has been amended to accommodate automated transport systems. The framework now allows for automated transport systems approval on the roads, subject to compliance with detailed safety criteria, aiming to protect vehicle occupants and vulnerable road users.¹⁵⁵Regulation (EU) 2019/2144 of the European Parliament and of the Council, 2019 O.J. (L 325) 1; Commission Implementing Regulation (EU) 2022/1426, 2022 O.J. (L 221) 1; see also FAQ – Type approval of vehicles, European Commission, https://single-market-economy.ec.europa.eu/sectors/automotive-industry/technical-harmonisation/faq-type-approval-vehicles_en (last visited Dec. 10, 2025).
Despite the detailed regulatory framework which has since emerged, there still has not been implemented a sustainable mobility focused regulation.¹⁵⁶On various aspects of the regulation, see, e.g., Kirchmair, supra note 137 at 1205; Leon R. Sütfeld, Joshua Bronson & Lando Kirchmair, Automated Vehicle Regulation Needs to Speak to Code, not to Humans: Keeping Safety and Ethics in the Public Domain, 38 Philosophy & Technology 15 (2025). Cf. on the sustainability aspect, see Gareth Willmer, Self-driving vehicles: the road to cheaper, sustainable urban transport in Europe, Horizon: The EU Research & Innovation Magazine (Apr. 22, 2025), https://projects.research-and-innovation.ec.europa.eu/en/horizon-magazine/self-driving-vehicles-road-cheaper-sustainable-urban-transport-europe.

C. The Regulation of Self-Driving Cars in Austria

Austria has likewise recognized the potential of self-driving cars and has passed regulations allowing for their deployment on Austrian roads, albeit with restrictions. The 33^rd and the 39^th amendments to the Motor Vehicle Act created the legal basis for the use of self-driving vehicles in test operation and for public use, respectively,¹⁵⁷Bundesgesetz, mit dem das Kraftfahrgesetz 1967 geändert wird (33. KFG-Novelle), BGBl I Nr. 67/2016 (Austria) [Federal Law Amending the Motor Vehicle Act 1967, Austrian Federal Law Gazette I 67/2016]. See also BGBl I Nr. 134/2020, amending e.g., §§ 34(4), 102(3, 3a, 3b) of the Motor Vehicle Act. On the question of regulating moral dilemmas in this regard, see Lando Kirchmair, Artikel 2 EMRK und die Notwendigkeit moralische Dilemmata verursacht durch selbstfahrende Autos (europaweit) zu regulieren, 1 Journal für Rechtspolitik 50 (2022).
leading to the issue of the AutomatFahrV [Automated Driving Ordinance].¹⁵⁸AutomatFahrV, BGBl II N4. 402/2016, amended by BGBl II No. 66/2019, BGBl II No. 143/2022 & BGBl II No. 287/2024 (Austria) [Automated Driving Ordinance, Austrian Federal Law Gazette II 402/2016; amended by Austrian Federal Law Gazette II No. 66/2019, Austrian Federal Law Gazette II No. 143/2022 and Austrian Federal Law Gazette II No. 287/2024].
According to Section 1(1) of this regulation, automated or networked driving systems may only be approved in the form of a parking aid,¹⁵⁹Id. § 10.
a highway assistant with automatic lane keeping,¹⁶⁰Id. § 11.
or in test operations.¹⁶¹Id. § 1(1)(2).
Moreover, Section 1(2) of the AutomatFahrV contains the condition that automated systems must ensure compliance with the Immissionsschutzgesetz–Luft [Air Pollution Control Act].¹⁶²Immissionsschutzgesetz–Luft, BGBl I Nr. 115/1997 (Austria) [Air Pollution Control Act, IG-L, Austrian Federal Law Gazette I No. 115/1997].
Beyond this, however, there are no special sustainability requirements for self-driving cars.

The Austrian ministerial Mobility Master Plan 2030 recognizes–mirroring the European Commission communication, examined above—the “significant potential” of cooperative, networked and automated mobility in passenger and freight mobility to reduce the negative climate and environmental impacts of transport.¹⁶³Mobility Master Plan 2030, supra note 78, at 44.
The Master Plan states remarkably clearly that “the realization of this potential [ . . . ] requires transparent, comprehensive and targeted control and steering by the public sector as well as a strong positioning of Austria in the international environment.”¹⁶⁴Id.
However, this has not yet been practically reflected in the legal regulation of self-driving cars in Austria.

V. Recommendations for Sustainable Mobility

Sustainable mobility is not just a description of environmentally friendly transportation; it is the recognition of the obligation to make transportation environmentally friendly without disregarding the social and economic pillars of sustainability. The principle of sustainability requires that the future environmental damage caused by the human urge to move around is kept to a reasonable level—without disregarding economic and social aspects, either.

The implications of the environmental pillar are twofold. First, policy and law should favor vehicles with lower CO₂ as well as other greenhouse gas emissions, for example, by incentivizing production and purchase of e-cars. In Austria, this was reflected in the “energy transition in transport” provisions in the Mobility Master Plan 2030. Second, the law ought to control user behavior to reduce emissions, for example through the use of “robotaxis” or “micromobility.” The Austrian Mobility Master Plan 2030 included these considerations under “transport transition.”

The social pillar of sustainability can be advanced by regulating the technological progress of self-driving cars in a way that adequately enables a more inclusive use of cars. The economic pillar, on the other hand, can be taken into account through such design of regulatory requirements that they do not prevent, stifle, or slow down innovation and technological progress. Instead, regulations should accompany and steer the technology with foresight, so that the pursuit of ecological goals does not neglect economic considerations.

Improving access to digital infrastructure—from access to internet networks and technology to e-government solutions—is essential to eliminate the necessity for physical travel to offices. Certain journeys, such as visits to public authorities, should not have to be done physically; instead, digital processes should ensure simplified access to the required services. Similarly, self-driving cars should be regulated in a sustainable way already at the design or purchase stage, and not only once they are deployed on the roads.

Financial incentives are a promising tool to make mobility more sustainable. Given the poor emission values in the transport sector, they should be used more frequently, in a targeted, context specific way. They can include subsidies, tax breaks, premiums, discounts, or penalties that aim to change behavior toward more environmentally friendly, efficient, and collective modes of transport. The range of incentives is wide, and the question of how these incentives should be used most efficiently may depend on the concrete goal, and socio-economic variables. According to empirical studies, it seems that particularly those incentives which lower the costs of sustainable vehicles at the moment of purchasing them, are effective. This should be picked up by regulation.

Lawmakers can therefore draw on a wide range of options if they actually wish to promote sustainable mobility. Naturally, since positive incentives are generally less intrusive than negative incentives, they should be used more frequently. To conclude with Arnie: it would be smart to choose “Door Number Two.”

* Prof. Dr. iur. habil.; Euregio Endowed Chair in Sustainability and Mobility Law, Department of Legal Theory and Future of Law, Faculty of Law, University of Innsbruck, Austria. This article is partly based on a lecture given at the Faculty of Law of the University of Innsbruck on September 11, 2024. The author is grateful to the audience and, particularly, to Sebastian Ambros, Matt Blaszczyk, Héctor Orlando Candray Medina, Alexandra Klass and Sebastian Krempelmeier for their helpful feedback as well as to Konstantin Friese and Ronny Wagner for their research assistance. Parts of this article have also been published in German. The author can be contacted at lando.kirchmair@uibk.ac.at.