Vehicle state analysis system and its analysis method

An engine performance map which specifies the relation between running conditions and brake specific fuel consumption (BSFC) is generated by estimating the BSFC relative to the engine rotation speed and accelerator depression amount, based on the BSFC characteristics predicted from the torque pattern of the vehicle being analyzed and the optimum BSFC. A vehicle mounted unit 1 computes the BSFC of the engine by looking up the engine performance map based on the engine rotation speed and accelerator depression amount, and computes the fuel consumption rate based on this BSFC.