N-butanol is a promising alternative fuel which needs no engine modification when used as a blend with diesel. The miscibility of n-butanol with diesel is excellent in a wide range of blending ratios. N-butanol has high oxygen content and a comparable energy content, specific gravity and viscosity to that of diesel, which makes it attractive for diesel engines as an alternative fuel. An experimental investigation was conducted to assess the performance of a new generation passenger car with respect to power, fuel economy (FE) and mass emission using 5, 10 and 20 percent (by vol.) n-butanol blends with diesel (NB). Computer controlled DC motor driven chassis dynamometer, AVL AMA I60 mass emission measuring system and AVL FSN smoke meter were used for measuring wide open throttle (WOT) power, road load simulation (RLS) fuel economy, mass emissions and smoke in WOT and steady speed driving conditions.The results indicated that the WOT power decreased with all blends of n-butanol in diesel. Vehicle specific fuel consumption (SFC) increased with increase of n-butanol fraction. The average steady speed fuel economy in the speed range of 40-80 kilometer per hour (kph) in RLS mode as well as driving cycle fuel economy has shown marginal reduction with all NB blends when compared with neat diesel. The New European Driving Cycle (NEDC) test results indicated that the carbon monoxide (CO), smoke and particulate matter (PM) decreased whereas hydrocarbon (HC) and nitrogen oxide (NOx) emission increased with all NB blends. Therefore, considering the properties and performance of n-butanol with diesel, it can be a promising second generation alternative biofuel for diesel fuel with respect to vehicle performance and emissions reduction.