This paper dynamically simulates a small running 2DW2C automobile (mouse) and simulates path tracking control. Our purpose was to optimize mouse design using simulation results. We added tire force and DC motor force to A1 Motion, a simulator for analyzing mechanical systems developed in our laboratory, and improved the simulator simulating a running automobile. Experiments with a small 2DW2C automobile compared experimental and simulation results involving dynamic characteristics of an actual mouse. We got correct simulation results using this model and simulator. We studied its running performance, affected by its wheelbase and caster length, and evaluated path tracking control using closoidal curves.