The impact of blending Ultra Low Sulfur Diesel (ULSD) with different biofuels, obtained from Rapeseed Methyl Ester (RME) and Hydrotreated Vegetable Oil (HVO) respectively, on the performance and emissions of a European passenger car diesel engine was assessed in this paper. First, the hydraulic behavior of the common rail fuel injection system was analyzed in terms of injected volume, injection rate, spray global shape, single jet tip penetration and cone angle with both RME and HVO blends in comparison with neat ULSD. Afterwards, the impact of biofuel blends on engine full load performance was analyzed, both for the standard calibration and for a calibration which was specifically adapted to biofuels characteristics. The effects of biofuel blends on brake specific fuel consumption and on regulated exhaust emissions were then evaluated at different part load operating conditions, representative of the New European Driving Cycle. Finally, the sensitivity of the different fuels to different calibration settings, such as Exhaust Gas Recirculation (EGR) and injection timing, was studied in order to investigate which further emission benefits could be achieved by means of a more extensive engine re-calibration. (C) 2015 Elsevier Ltd. All rights reserved.