The joint research on fuel and vehicle technology influence on emissions is being conducted in the Japan Clean Air Program (JCAP). JCAP program aims to clarify the fuel influence on emissions with the conventional and advanced vehicle technologies such as lean burn and direct injection. The gasoline working group of JCAP investigated the effect of combination of vehicle technologies and various fuel components (such as sulfur and aromatics). The program consists of two parts, Step l and Step ll. This paper describes the result of the Step I program on the Japanese 10-15 mode and 11-mode on 19 vehicles including motorcycles. An emission decrease with sulfur content reduction was confirmed by most of the test vehicles. This was more significant on the lean burn engines and direct fuel injection engines with a NOx storage-reduction type catalyst emission control system. The sulfur effect was also found for the early light off catalyst system in the cold mode (11-mode). The influence of the aromatics was also confirmed on THC and CO except NOx. Evaporative emission tests shows that lower RVP fuels and some vehicle technologies such as larger canister capacity, lowering fuel tank temperature are able to reduce the evaporative emissions.