—The increase of urban traffic confronts individualsand transport authorities with new challenges regarding trafficmanagement, personal mobility, sustainability, or economicefficiency. Existing resources cannot be arbitrarily extendedwithout negative effects on pollution, costs, or quality of livingand have to be used more efficiently. The SUNSET(Sustainable Social Network Services for Transport) projectaims to improve this situation on a city-wide level bymotivating users on a personal level to change their mobilitybehavior. To make personal mobility more sustainable,flexible, and rewarding for users, SUNSET combines mobilitydata and patterns from mobile sensing, a dynamic incentivesystem, and feedback from social networks. This paperdescribes how the tripzoom application implements thisconceptual approach, discusses critical issues and outlines theforthcoming living lab evaluation in several European cities.