With scientific discoveries indicating a relationship between nitrogen oxides/particulate matter and cancers/heart disease, and the growing road transport sector in Western Europe, there is an increasing urgency to further reduce vehicle emissions. This comprises a large part of the total emissions in urban areas. In this article, we address the question of how various local policy instruments and technology can be used to support the use of clean road vehicles in urban areas. Despite some moderate success in specific areas, local policies and technology need to become even more effective. Using the STREAMS model, a comparative analysis is made of six urban cases in the Randstad and the Rhine-Ruhr metropolitan areas. The study provides new insights into the dynamics between the perceived problems, policy making (in terms of the adoption of policy instruments), politics (in terms of the fit/misfit between stakeholders' interests, which may result in a window for policy change), and technology. The policy instruments examined include low emission zones, parking licence restrictions, and incentives to adopt electric vehicles. Policy recommendations are made regarding effective policy instruments for the reduction of harmful emissions in metropolitan areas. Implications for theory are also discussed.