This paper reports an initial evaluation of gasoline composition effects on exhaust emissions in European vehicles tested over European emissions test cycles.In Phase I of this work, 3 European vehicles (2 old and 1 new technology) were tested on the US Auto/Oil non oxygenated fuel matrix, as well as on one European fuel, with and without MTBE. In Phase II, a fuel matrix based on European gasoline components was evaluated (a) in 3 vehicles (1 old and 2 new technology) and (b) in another new technology vehicle, tested with and without its catalyst fitted. Detailed hydrocarbon speciation was included in (b).The main conclusion from this work is that vehicle technology plays the major role in exhaust emission control. The recent introduction of catalyst equipped cars and sophisticated engine management systems into the European fleet will provide significant environmental benefits. Fuel effects tend to be small, highly variable and vehicle dependent, particularly with modern adaptive learning engine management systems where the control system corrects at least partly for fuel stoichiometry. Clearly fuel composition effects need to be evaluated in a much wider range of vehicle technologies to provide a more complete picture of the relative influences of engine design and fuel composition on emissions. Future studies also need to consider the relationship between vehicle emissions and environmental impact, real air quality needs in Europe and cost/benefit analysis for any refinery or vehicle changes.