Abstract: Accurate estimation of vehicle transient fuel consumption is a fundamental part of the energy-saving control. For the steady-state fuel consumption model, it is affected by many factors such as the non-linear working characteristic of the engine, driving habits, driving environment, driving state, vehicle load etc. The transient fuel consumption calculated by the model deviates greatly from the actual fuel consumption. For the existing transient fuel consumption model, the parameters are difficult to calibrate. Therefore, a new model utilizing vehicle speed and acceleration is built to estimate the instantaneous fuel consumption, and the least square method is employed to identity the parameters in this new model. In order to lower estimation error of the transient fuel consumption, exponential attenuation factor is added into the least square method, i.e. the least square method with exponential attenuation factor is utilized to identify the parameters of the new fuel consumption model. The effectiveness of the new fuel consumption estimation model is tested experimentally. The result shows that the new fuel consumption model based on the least square can estimate transient fuel consumption accurately, and that the fuel consumption model by the least square method with exponential attenuation factor produces lower estimation error and its estimation accuracy is hardly affected by the factors such as the driving state of the vehicle, the road environment, etc

Key words: estimation of instantaneous fuel consumption, instantaneous fuel consumption model, lest square, lest square with attenuation factor (LSWAF)