Future cooperative traffic safety applications based on vehicular networks rely heavily on the support for real-time inter-vehicle communication. The Medium Access Control (MAC) mechanism proposed for the upcoming IEEE 802.11p standard intended for Intelligent Transport Systems (ITS) applications does not offer deterministic real-time support, i.e., the channel access delay is not upper bounded. In this paper, we therefore propose a vehicle-to-infrastructure(V2I) communication solution extending IEEE802.11p by introducing a collision-free MAC phase based on real-time schedulability analysis. A static or semi-static access point on the road side (Road Side Unit, RSU) coordinates the vehicles’ access to the communication medium by polling them for data according to a schedule based on the Earliest Deadline First (EDF) principle. It is thereby possible to provide real-time support such that the access point can guarantee collision-free channel access within its transmission range. Part of the bandwidth remains unchanged and best-effort services like ongoing vehicle-to-vehicle (V2V) applications can continue. We enhance our MAC solution by introducing a prioritization mechanism based on vehicle positions and the overall road traffic density, which leads to a more efficient use of the available bandwidth and further improves the real-time capabilities of our solution.