By Henrik Becker, Francesco Ciari, Massimo Brignoni, Kay W. Axhausen, IVT, ETH Zurich
The purpose of this paper is the discussion of the environmental effects of a free-floating car-sharing system operating in Ulm, Germany. The system, called car2go, allows users to take and leave vehicles at any point within the city limits. Thus opposed to traditional car-sharing, there are no fixed stations and in particular one-way trips of any length are possible without a booking requirement. Since this is the first free-floating system in operation, there is as yet no associated empirical research. Based on primary data from a survey, a model was developed to forecast the environmental impact of car2go. The prognosis considers the period of five years after the launch of car2go in 2009 and indicates a CO2-reduction per average car2go-user. In addition, more than a quarter of the survey respondents stated that they may forgo a car purchase if car2go was offered permanently. By reaching a greater share of citizens than traditional systems, the results indicate that free-floating car-sharing systems could contribute to reducing private vehicle ownership in cities.

According to preliminary analyses, the collected data allows to clearly identify the different
user-groups and motivations of station-based and free-floating car-sharing members in both
socio-demographic variables and travel behaviour. Moreover, using the wealth of diary data, it
can be observed, when and how members of the different survey groups use specific transport modes.