Usually, vehicle fuel economy and driving performance mostly are determined by field test or on proving grounds. This paper presents a method to develop a model for the simulation of vehicle fuel economy and driving performance on microcomputer. The model is derived from engine fuel consumption Hap and its characteristics Curve, or from the original engine test data. By incorporating them with the equations of driving performance in terms of vehicle speeds, this computational simulation model is established. Based on this model, a program named CQ-1 with its block flow chart and function module was made. As an example, a heavy duty truck Hong Yan CQ19210 was taken for simulation. The accuracy of simulation has been evaluated by comparing its results with that of test. The factors influencing the simulation accuracy will be discussed in this paper.