MOBILEL is a two-year demonstration project sponsored by the Swedish Energy Agency, the City of Stockholm and FORTUM power and heat company. The main objective for the participation in MOBILEL is to evaluate the feasibility of so called plug-in vehicles, with regards to user aspects, through a field trial. Five Toyota Prius will be equipped with a larger battery pack to increase the driving range in electric vehicle mode. The environmental benefit will be lower energy consumption, reduced carbon dioxide emissions, less local emissions and less noise. The demonstration will then be assessed considering user requirements, charging infrastructure, environmental effects etc. The Stockholm trial serves the important purpose of creating knowledge and debate around plug-in vehicles powered with electricity and demonstrating new technology. Also, important knowledge will be created about the ITS potential in linking these kind of vehicles and infrastructure, but also in different means of assisting drivers to make smart choices.