Vehicle platoon is the technique in which vehicles run in line with short vehicle distance, which is considered as the important application of intelligent transportation systems (ITS). The aim of this study is to design the mathematical model for velocity control of vehicles in vehicular platoon. The mathematical model is often defined by car-following model that controls the velocity according to vehicle distance, vehicle velocity distance and so on. In the previous study of our laboratory, Bierley model and its extension were used for the vehicle velocity control [1]. This study will discuss the improvement of the previous model by incorporating the amount of change in the speed of the vehicle in front. The platoon is composed of ten vehicles in computer simulation. The leader vehicle of the platoon suddenly decelerates and accelerate again. The velocity fluctuation of vehicles is discussed in computer simulation. The results show that the new model has a shorter convergence time than that of the previous model and the maximum speed of the last vehicle is also smaller. Therefore, the new model can realize a smoother speed than the previous one.