A number of commercially available and viable diesel fuels of different specifications was tested in two passenger cars powered by advanced prototype IDI and DI diesel engines, respectively, along the FTP 75, FTP 72 hot, the new European driving cycle [ECE 15 (urban) + EUDC (extra urban driving cycle)] cold and hot, and the Japan 10.15 driving cycle (hot start test). Both engines have been developed for emission levels currently required in Europe for diesel powered passenger cars.The results of this study demonstrate that fuel quality does have a significant impact on exhaust emissions of advanced diesel engines of both, DI and IDI combustion technology. The observed differences in emissions could be correlated with cetane number, density or aromatics content of the fuels tested whereas correlations with the distillation range (90% boiling point) was rather poor. However, the intercorrelation of the fuel properties did not enable to unambiguously identify the key fuel property governing emissions. As expected, gaseous emissions - though at low levels in both cases - turned out to be lower with the IDI diesel engine, while total particulates and fuel consumption were lower with the DI engine. This behaviour was observed in all test cycles and with all fuels tested.