Vehicle-to-vehicle communication systems promise enhanced safety for passengers, but require access to a crowded wireless spectrum to enable their data links. Simultaneous Transmit and Receive (STAR) systems can facilitate this spectrum access by increasing the number of users within a given frequency band. Since high isolation is needed for STAR system operation, the effect of mounting a STAR antenna on a vehicle is investigated in this paper. The omni-directional antennas isolation performance was measured to be 53 dB at 2.45 GHz across a 60 MHz bandwidth, which confirms that the vehicle does not significantly degrade isolation performance.