Vehicle sharing is one of the possible answers to the increasing demand of sustainable way of transport. However, the traditional management models of sharing services are not flexible enough to be a real answer to current and future mobility needs. Green Move, an ongoing project financed by Regione Lombardia that involves eight different research centers of Politecnico di Milano, has the objective to design and test a vehicle-sharing system, with different categories of electric vehicles. The service will have the following characteristics: multi-ownership, allowing single users, private companies, and associations to join the service both using vehicles provided by the service itself and sharing their personal electric car or fleet, this represents an application of a peer2peer approach in the field of sustainable mobility; the Green e-Box, a device that will be the bridge between user, vehicle and control center, potentially compatible with any vehicle; key-less-mobility, meaning that personal smartphones will be the accesskey to the Green Move fleet, avoiding the use of smart-cards or physical keys. The design of a full scale service for the city of Milano will be carried out by a multi-criteria assessment of a wide number of possible alternative options in order to identify the most feasible and effective one. Indicators will be identified to measure the performance on relevant dimensions (i.e. economic and financial sustainability, social benefits, environmental effects). A trial to test the operating modes and the service efficiency will be carried out with electric vehicles and docking stations in a specific area of Milan, establishing a connection with the present traditional electric car sharing service owned by the Region. The performance of the service in term of accessibility and usability will be measured with a specific monitoring system. The paper aims to give a general overview of the project and a focus on the methodology in use for the full scale service design.