A wireless unit for a wireless vehicle system includes a receiver for receiving a vehicle-originating signal, a transmitter for transmitting a reply signal, a received signal strength indicator (RSSI) for determining a received signal strength of the vehicle-originating signal, a memory for storing sensitivity data, and a control unit in electrical communication with the receiver, the transmitter, the RSSI and the memory. The receiver has a sensitivity, and the memory is for storing sensitivity data corresponding to the sensitivity of the receiver. The control unit is configured to communicate with the transmitter to direct the transmitter to transmit the reply signal. The reply signal includes received signal strength data used for determining a distance between the wireless unit and an associated vehicle-side transmitter on an associated vehicle. The received signal strength data is based on the received signal strength and the sensitivity data.