The driver and road environment had most influence on vehicle handling and stability, when vehicle was of high speed. The evaluation model of lateral dynamics with driver model of single point preview optimal curvature and road model of slalom based on driver-vehicle-road closed-loop system was built. It considered the influence of driver’s response. The slalom test suggested the rhombic vehicle has good handling and stability, and the comparison between the simulation of the driver-vehicle-road closed-loop model and the slalom test proved that the result has good consistency.