How car sharing can contribute to better cities
12.08.2025
Rebecca Karbaumer is responsible for sustainable mobility in the City of Bremen and coordinates European projects relating to shared mobility. She has been a member of the Mobility Board of Directors since 2022. This text is an excerpt from her presentation at the Mobility Delegates’ Meeting 2025.
For many, car sharing is a secondary issue – for me, it’s a key tool for the mobility revolution. It’s about much more than just CO2emissions. Sustainability in urban areas is considerably more complex and also encompasses social, spatial and economic aspects. From my work in Germany and throughout Europe, I know that shared mobility can help make our cities fairer, more livable and more efficient.
Rethinking sustainability
All too often, sustainability is reduced to CO2emissions. Of course, these emissions are a problem – but not the only one. Cities today suffer from heat waves, heavy rain, noise, fine dust, space problems and social inequalities. Public space is limited. Many European cities were built for a time before vehicles. And yet vehicles take up most of this space – and are often stationary.
It’s also about justice – who has access to the space? Who benefits from the infrastructure? Accessibility, participation, safety for all age groups – these are just as important sustainability goals as reducing emissions.
Shared mobility as the key
In this complex situation, shared mobility offers specific answers. I’m certain that car sharing is part of environmentally friendly, socially fair and affordable mobility that starts with pedestrian and cycle traffic and complements the environmental network. A sustainable mobility pyramid (see diagram) gives everyone access to mobility. It starts with modes of transport that are accessible to everyone and ends with private, more resource-intensive means of transport.
Numerous studies confirm that car sharing users drive less, are more active and use public transport more often than the average car owner. Car sharing users are also much less likely to own their own vehicle.
Save space instead of parking metal
One impressive picture that I often show in presentations is the “12 square metres”: That’s how much space a single parking space takes up – space that is lacking in many cities. This area corresponds to a children’s bedroom or several parking spaces for bicycles or cargo bikes. When we ask people what they want in their home, the answer is not usually more parking spaces. They say they want more living space.
Car sharing as a brake on costs
Car sharing not only takes the strain off the environment, but also off household budgets – both those of users and those of cities. Public parking costs municipalities a lot of money, while neighbourhood garages are expensive, especially if they are planned underground. In new construction projects, car sharing can save hard cash – both for investors and for residents.
In Bremen, for example, the parking regulations for new construction measures require investors to submit a mobility concept that includes mobility management measures (car sharing might be one of the components included in this concept). As a result of this, the investor has to build significantly fewer parking spaces for cars. This means that integrating a mobility concept saves money.
In a study, I recently questioned the assumption that apartments without a parking space cannot be sold. The result: The majority of people not only approved but strongly endorsed the fact that they were offered alternatives such as car sharing instead of a parking space when they moved in.
Electrification – important, but not the be-all and end-all of sustainability
I often hear the remark that car sharing is only sustainable if it is electric. My answer: E-mobility is important, but it doesn’t solve the traffic problem. It is parked cars that cause traffic problems. Even if all these vehicles were electric, traffic jams, space consumption and resource requirements would remain the same.
«When it comes to reducing emissions, the growth in car sharing utilisation is far more effective than fleet electrification»
Car sharing reduces traffic and space requirements due to parked cars – regardless of the drive system. And when it comes to emissions from transport, mobility behaviour is the decisive factor! This can be seen in the following example: In Bremen, for example, the 28,000 or so car sharing users save 24,000 tonnes of CO2 per year thanks to their mobility behaviour. If the entire Bremen car sharing fleet were to be electrified overnight (currently around 639 vehicles), this would only amount to around 2,300 tons of CO2which could be saved annually. The cost: an investment of 4 to 5 million Euros – for charging infrastructure alone. On the other hand, only a customer growth of between 400 and 800 people would have the same CO2effect as the complete electrification of the fleet. In other words, the growth in car sharing utilisation as a whole is much more effective if you really focus on reducing emissions in transport.
The wrong button: greenhouse gas reduction quotas
Politically, greenhouse gas reduction quotas for car sharing are the subject of constant debate. They already exist in Amsterdam, Hamburg and Antwerp. However, the industry is already way ahead of the private market. In Switzerland, 20% of Mobility vehicles are electric, while with private cars it’s only approximately 4%. In Germany, the share is 18% of all car sharing vehicles compared with 2.9% privately owned. In other words, the car sharing industry is already electrifying in an exemplary manner – but with a sense of proportion, according to the needs of customers and the opportunities offered by the infrastructure.
What car sharing really needs now
When I talk about sustainable growth, I mean more locations, more vehicles, more customers. Overall, it must be possible for people to drive less. This requires good public transport services as well as opportunities to walk and cycle – regardless of socio-economic status or physical ability. And if people need to or want to drive a car, car sharing has to make it possible – just as easily and conveniently as using your own car. After all, that’s our biggest competitor – the private car.
What a private car can do very, very well is to be available on my doorstep at all times and to give me the subjective feeling of freedom. This means that we can only really make an impact if we achieve this proximity and feeling for a wider audience through car sharing.
My conclusion
Car sharing is more than just a Mobility offer. It’s an answer to the pressing questions of the time, especially in cities: Space, climate, social fairness. For providers such as Mobility, the focus should be on expansion, accessibility and user acquisition – not on technical symbolism. The most sensible electric car remains the shared one.