VANETs aim to improve traffic safety and driving experience on the road. A medium access protocol for VANETs determines their performance. A key challenge in the design of MAC protocol is timely and accurate delivery of messages even when network topology changes quickly. In this work, we propose enhancements in the native SDMA protocol to suit safety critical message transfer in VANETs. In the proposed enhanced SDMA, the road is logically divided into spatial slots and TDMA time slots are assigned to each spatial location. In Enhanced SDMA, the spatial slot allocation is done using the vehicular traffic distribution. The empty slots in sparse traffic and paucity of slots in congested traffic are allocated to optimize the fairness in channel distribution and throughput maximization using SINR (Signal to Noise and Interference Ratio). Simulation results indicate the Enhanced SDMA is able to achieve both efficient slot allocation and enhanced throughput for both free flow and congested traffic states.