This report from the Technology and Policy Assessment (TPA) function of the UK Energy Research Centre examines the merits of a range of different policies that offer the prospect of carbon dioxide (CO2) emissions reduction from road transport. The evidence on each policy is reviewed against the following criteria: (1) potential emissions saving; (2) key issues and problems, including reasons for effectiveness, evidence gaps, obstacles to policy implementation, interactions with other policies, and potential rebound effects; and (3) costs. This report does not undertake new modelling or empirical research; rather it provides a thorough review of the current state of knowledge on the subject, guided by experts and in consultation with a range of stakeholders.