Simply input your location information into the Avis Assist handset, or call an Avis Advisor with your desired destination address. The server uses GPS location from the phone as the starting address, calculates the route and downloads it. The handsets speakerphone then issues "turn-by-turn, street specific directions" through the speakerphone.
If a wrong turn is taken, the directions suggest the driver pull over and wait for the route to be recalculated. The service uses Motorolas VIAMOTO GPS, JAVA and LBS software. Motorola and Avis have rolled out the service in 57 US cities.