Fatty Acid Methyl Ester (FAME) products derived from vegetable oils and animal fats are now widely used in European diesel fuels and their use will increase in order to meet mandated targets for the use of renewable products in road fuels. As more FAME enters the diesel pool, understanding the impact of higher FAME levels on the performance and emissions of modern light-duty diesel vehicles is increasingly important. Of special significance to Well-to-Wheels (WTW) calculations is the potential impact that higher FAME levels may have on the vehicle's volumetric fuel consumption.The primary objective of this study was to generate statistically robust fuel consumption data on three light-duty diesel vehicles complying with Euro 4 emissions regulations. These vehicles were evaluated on a chassis dynamometer using four fuels: a hydrocarbon-only diesel fuel and three FAME/diesel fuel blends containing up to 50% v/v FAME. One FAME type, a Rapeseed Methyl Ester (RME), was used throughout. One vehicle was equipped only with an oxidation catalyst while the other two were also equipped with two types of Diesel Particulate Filters (DPFs). In addition to CO₂ emissions, regulated tailpipe emissions (NOx, HC, CO, PM, and PN) were collected in order to evaluate the impact of higher RME contents on emissions performance.The results obtained over the New European Driving Cycle (NEDC) indicate that the volumetric fuel consumption systematically increases with increasing RME content for all three vehicles. Within the statistical precision, the vehicles were not able to compensate for the lower energy content of the RME/diesel blends and consumed more fuel in direct proportion to the lower energy content of the RME/diesel blends.As the RME content of the fuel increased, the particulate mass (PM) and solid particle number (PN) were generally found to decrease over the NEDC while the NOx, CO, and HC emissions increased. The overall impact of RME on regulated tailpipe emissions is much smaller, however, compared to the variations in emissions seen over the NEDC sub-cycles.