In an article for the journal “Nature Sustainability“, three scientists from the Fraunhofer Institute for Systems and Innovation Research ISI and a colleague from the Simon Fraser University, Canada, analyse the design of car bans. They investigated both sales bans and access restrictions. The former have been announced at national level and prohibit the sale of diesel and petrol vehicles from a certain point in time to reduce CO₂ emissions. Access restrictions, on the other hand, usually focus on air quality in an urban area and exclude vehicle types with certain drive trains.

The key result: although car bans can help reduce greenhouse gas emissions and improve air quality, they are not designed properly. The authors criticise, in particular that the bans often only exist as announcements and objectives, but lack enforcement mechanisms. And where legal requirements exist, they are often inadequately monitored, and infringements are usually not penalised at all.

Worldwide, the authors have identified 13 nationwide bans which have been announced, four regionally planned targets and 18 plans at city level that include a complete ban on driving or selling vehicles with internal combustion engines. The access restrictions which are in place in Germany in environmental zones or cities burdened with high amounts of particulate matter such as Hamburg or Stuttgart are not included, as only older vehicles are affected in these areas.

Planning security and a mix of other policy instruments are important

In general, the authors emphasise that there must be explicit enforcement and explicit timetables for any kind of ban. In order to achieve the target of zero CO₂ emissions in 2050, the ban on the sale of diesel and petrol vehicles with conventional fuels would have to be introduced between 2035 and 2040 due to the average passenger car lifecycles of about 15 years.

In order for all those affected to be able to adapt, timely announcement and the gradual introduction of, for example, slowly increasing quotas for sales of electric vehicles are needed. It is also possible to ban pure petrol and diesel vehicles first and hybrid vehicles at a later date. “However, these steps must be taken consistently and be announced in good time“, says Patrick Plötz, lead author of the study.

According to the article, it is also important to link the restrictions with other policy measures: e.g., electric and hydrogen vehicles need sufficient infrastructure for the market uptake. The expansion of public transport and non-financial incentives such as free parking for electric vehicles would also support the path towards sustainable mobility.

In the authors' opinion, car bans alone are no panacea for low CO₂ traffic. But if they are consistently planned and combined with other policy measures, they can make an important contribution to achieving long-term greenhouse gas reduction and clean air targets.

The Fraunhofer Institute for Systems and Innovation Research ISI analyzes the origins and impacts of innovations. We research the short- and long-term developments of innovation processes and the impacts of new technologies and services on society. On this basis, we are able to provide our clients from industry, politics and science with recommendations for action and perspectives for key decisions. Our expertise is founded on our scientific competence as well as an interdisciplinary and systemic research approach.