In vehicular communications, the channel estimation is critical to compensate signal distortion due to wireless channel in high mobility scenario. To improve the error performance of vehicular communications, we proposed the midamble-based channel estimation scheme. Based on the proposed scheme, we investigate the effect of midamble insertion on the system performance. With various midamble insertion rates, the error performance for the system with different modulation scheme, packet size, and channel condition is explored. The effects of various factors on the error performance are also developed.