Many studies indicate that multi-event accidents have higher risks and injuries than a single accident. Larger heading angle and lateral deviation could be produced by impulsive impacts, which result in severe accidents. Active safety technology can be applied for controlling the motion after impact. In this paper, a sub-optimal second-order sliding mode (SSOSM) controller based on a three degree of freedom vehicle model is designed to mitigate the undesired motion after a fictitious impact. The controller is verified through high fidelity co-simulation platform Carsim and MATLAB/Simulink. The simulation results show that the SSOSM controller gives better control performance for tracking the desired heading angle and lateral deviation from the path. The chattering phenomenon of sliding mode is decreased and smooth results are given.