In this paper, the bit error rate (BER) performance of SM systems under a novel three-dimensional (3D) vehicle-tovehicle (V2V) multiple-input-multiple-output (MIMO) channel model is investigated both theoretically and by simulations. The impact of vehicle traffic density (VTD), Doppler effect, and 3D and two-dimensional (2D) V2V MIMO channel models on the BER performance are thoroughly investigated. Simulation results show that the performance of SM is mainly affected by the spatial correlation of the underlying channel model. Compared with other MIMO technologies, the SM system can offer better tradeoff between the spectral efficiency and system complexity.