High reliability and spectral/power efficiency are key metrics for vehicular communications. The former is due to the requirements for the safety and route related information transmitted; while the latter owns to the conflict between the communication demands of user and limited capacity of vehicular batteries. Bearing these in mind, in this paper we propose a novel quadrature index modulated OFDM system by independently performing the index modulation in both in-phase and quadrature domain. We give the detailed transceiver design of the proposed system and evaluate the performance through theoretical analysis and simulations. Results demonstrate that the proposed scheme outperforms the traditional OFDM-IM with the same spectral efficiency in various mobile scenario.