The paper presents a mathematical model of a motion control system for a vehicle with a chassis of two independent drive wheels. The active wheels are driven by DC motors through the reducers. The vehicle has a wheel speed sensor and a sensor of the lateral deviation from the predetermined route, a signal from which is transmitted to the control unit. The model takes into account the position of the wheeled mobile vehicle in relation to a guide path. It is built with the transfer functions, which allow application of the methods of both classical and modern control theory for the synthesis of the control devices. The model of the vehicle describes three interrelated subsystems, which control the lateral deviation, the longitudinal velocity and the position. Research of each subsystem separately showed theirs drawbacks. The lateral deviation control has a large overshoot and settling time. The longitudinal speed control has an error in steady state. The drawback of the position control is the presence of an overshoot, which demands the reverse engines. These drawbacks can be eliminated by introduction of the control devices into each of the subsystems. Also, the model envisages a trajectory of the vehicle motion in the coordinate plane. Besides, it provides for a model of the trace, defined in the deviations from the straight direction. This model takes into account the presence of the straight sections, the turning sections and the positioning points on the trace. The developed model is useful for a preliminary research of the synthesized control laws of the vehicle motion.