The goal of STARS is to close the gap between the potential benefits of shared vehicle services, with special emphasis on those innovative forms that are enabled by recent technology applications in the transport sector, and their real impacts in terms of congestion mitigation, environmental footprints and social inclusion, that are mediated by both individual preferences and social innovation patterns. STARS will achieve this goal by integrating knowledge, expertise and research methods from transport engineering, environmental psychology and economics, thanks to the unique blend of different competences and kinds of organisation within the consortium. The role of car sharing in improving mobility in European urban areas and providing new business opportunities to the automotive sector will be assessed through an integrated co-modality approach, where the impact of car sharing on other travel modes (public transport, active means, private cars) will be quantified. To this effect, both business as usual and rupture mobility scenarios will be studied, the former referring to future projections of actual trends concerning the diffusion of car sharing in EU countries, and the latter to an assessment of its full potential in presence of appropriate policy actions aimed at maximising social benefits. These policy actions will be informed by the definition of a decision support toolkit that will allow the identification of the best strategy to implement a car sharing service (kind of service to promote, rough estimation of the market dimension, accompanying measures for competing travel modes, business opportunities for different economic actors) as a function of the socioeconomic characterisation of the area, of the related mobility lifestyles, of the policy context and of the related Sustainable Urban Mobility Planning measures and priorities. Both guidelines (in the form of what-if scenarios) and practical examples will be provided.