Orthodox economics sees transport as a market which can be made more sustainable by improving its self-regulating capacity. To date this static approach has not been able to limit the growing demand for transport and its increasing environmental impact. Better results might be obtained by using evolutionary and institutional economics. Starting from these theories, a sustainable transport policy should be based on three fundamental considerations. First, transport is not a market, but a sum of systems affected by path-dependence and lock-in phenomena. Second, transport is not sustainable because it is locked in environmentally sub-optimal systems. Third, structural changes in technologies and organisations, institutions, and values are needed to establish more sustainable transport systems. We give an example of the use of an institutional/evolutionary approach to sustainable transport policies in the transition from the system of mass motorisation to the new urban mobility system.