—Communication between cars can be exploited for various applications. Security enhancements as well as interactive games played by occupants of different cars are only two examples. The IEEE 802.11p standard will specify physical and MAC-layer for such scenarios. As one of the design goals is to partially reuse existing WLAN technology we investigate in this paper the performance of IEEE 802.11a, 802.11b and 802.11g devices in car-to-car (C2C) as well as car-to-roadside (C2R) scenarios. The determined performance is mostly independent of the car velocity up to the maximum measured speed of 180 km/h. The major impact factors found are the C2C distance, the availability of line-of-sight between sender and receiver and the rate adaptation algorithm.