In Thailand, in order to reduce fossil fuel demands, plam biodiesel has been mainly focused as an alternative fuel. The use of biodiesel could not only support the environmental sustainability but also foster the self-sufficiency economy concept in the country. However, there are some questions regarding fuel compatibilities with modern vehicles, especially the implement of biodiesel in common rail engine. Hence, the objective of this study is to investigare a long-term effect of using palm biodiesel in common rail vehicle. A commercial van with common rail system for four-cylinder direct injection was fueled with neat palm biodiesel and operated continously on real condition for a total of 60,000 kilometers. After each 20,000 kilometer test interval, the performance of the tested van was assessed on chassis dynamometer and evaluated according to the Bangkok standard driving cycle. Engine performance, fuel consumption and exhaust emissions (CO, CO2, NOx, and THC) were determined and compared to the initial values. The obtained results indicated that the tested van was successfully operated with neat palm biodiesel for a total running distance of 60,000 kilometers without any significant deterioration of engine performance and emissions