The increase of urban traffic confronts individuals and transport authorities with new challenges regarding traffic management, personal mobility, sustainability, or economic efficiency. Existing resources cannot be arbitrarily extended without negative effects on pollution, costs, or quality of living and have to be used more efficiently. The SUNSET (Sustainable Social Network Services for Transport) project aims to improve this situation on a city-wide level by motivating users on a personal level to change their mobility behavior. To make personal mobility more sustainable, flexible, and rewarding for users, SUNSET combines mobility data and patterns from mobile sensing, a dynamic incentive system, and feedback from social networks. This paper describes how the tripzoom application implements this conceptual approach, discusses critical issues and outlines the forthcoming living lab evaluation in several European cities.