What part of the car is tracked?

With waypoints the car goes to the waypoint but what part of the car is tracked by waypoints? for example the whole car goes through the waypoint but I dont know if the whole car is tracked or a node or a part of the car?

I need to know because my scenario will include any part of the car passing the finish line is the winning car, for example a tire comes off and rolls past the finish line before any other car.