Computer simulation of three vehicle motions has been made possible over a range up to high lateral acceleration. These three motions are stationary circular turning motion, slalom motion, and straight-running motion (against disturbances) selected as fundamental motions for evaluating vehicle handling and stability. The mathematical model is a nonlinear one with seven degrees of freedom and 63 design parameters. The validity of this model has been confirmed experimentally.As for slalom motion, critical slalom speed with pole interval used as a parameter has been obtained theoretically. In the process, some of the slalom characteristics that are known experimentally and empirically have been substantiated by assuming driver's perception and physical limits relative to steering.