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Car Sharing Systems as a Sustainable Transport Policy: A Case Study from Lisbon, Portugal

Sustainable Urban Transport

ISBN: 978-1-78441-616-4, eISBN: 978-1-78441-615-7

Publication date: 13 May 2015



The dominance of road transport, both on passenger and freight movements, has reached alarming levels in what concerns their negative environmental impacts as well as societal and economic costs. To reverse this trend, a technology-driven approach and a behavioral change attitude need to be pursued. Promising results have been reported in Europe in the reduction of vehicle ownership, due to the introduction of an alternative transport mode known as car sharing. This work evaluates the contribution of car sharing to sustainable transport, based both in a technological shift and a potential behavioral change.


The state of the art on car sharing and policies presents the effects of these systems and how they have been promoted. As those effects can vary according to the geographical area, the users profile, and service characteristics, a worldwide analysis on car sharing systems covering more than 400 cities was performed. Average service indicators were quantified and characterization variables were accounted to those cities’ urban areas. Considering those normalized values, the authors performed an analysis of the car sharing system in Lisbon (Portugal). An initial assessment was made to estimate its current energy and environmental impacts. This outcome was then compared with the environmental and economic effects of using alternative vehicle technologies in car sharing. The results obtained enable a discussion of the more important variables for the success of the system and, consequently, to choose what policy instruments can help car sharing to succeed.


The results of the existing car sharing schemes reveal the positive contribution of car sharing to fill a “mobility gap” in sustainable transport. It works as a complement to other sustainable transport options and it impacts positively both society and car-sharers in terms of mobility costs, environmental, and energy implications. These results are more significant if a technology shift to electric mobility is promoted. Within the case study in Lisbon, the adoption of electric mobility would allow decreases up to 47% and 65% in energy consumption and CO2 emissions, respectively. Moreover, the present value economic analysis revealed that, these systems will only be economically viable after approximately 7 years. A sensitivity analysis to the economic model was performed showing that the variables having higher influence were cost-related variables (reducing the break-even timeframe from 36% to 57%), such as vehicle purchase cost, insurance, maintenance and tax costs, and fuel cost.

Social implications

Car sharing systems generally present social benefits to society as it leads to the reduction of car ownership, with all the positive effects that has on a lower demand for parking space, less congestion, reduced local pollutants and emissions. If the technology used by car sharing vehicles shifts from conventional to another type of technology, the effects both for society and car sharers are even more appealing from a social point of view. In the particular case study approached in the chapter, given the small scale of the car sharing network and low usage patterns, the local results have a low social impact at the city scale. A larger promotion of the system either with a more aggressive marketing campaign targeting specific population niches (e.g., environmentally conscious people), larger vehicle and parking availability, or better integration with the city’s public transport system could foster the deployment of the system, similarly to other cities.


Overall, the results obtained from this research work quantify the contribution of car sharing to sustainable transport and highlights the positive effects of promoting a technological shift. These facts reinforce the need for public policies to support the integration of car sharing within the city’s solutions to promote a more sustainable mobility. The successful deployment of car sharing systems can be influenced by policies targeting features such as allocation of parking, the fees and complementarity with public transport, signage and markings, and marketing of social and environmental benefits.




Thanks are due to Fundação para a Ciência e Tecnologia for the Post-Doctoral (SFRH/BPD/79684/2011 and SFRH/BPD/74080/2010) and PhD financial supports (SFRH/BD/80500/2011). Thanks are also due to MobCarsharing for providing data. This work was also supported by FCT, through IDMEC, under LAETA, project UID/EMS/50022/2013.


Baptista, P., Melo, S. and Rolim, C. (2015), "Car Sharing Systems as a Sustainable Transport Policy: A Case Study from Lisbon, Portugal", Sustainable Urban Transport (Transport and Sustainability, Vol. 7), Emerald Group Publishing Limited, Bingley, pp. 205-227.



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