Well even if it wasn't unlimited, you wouldn't be likely to run it empty while playing AH anyway.
Take a Jeep for example. Lets say it gets 10 MPG, and the tank hold 10 gallons (for simplicity). That means you'd have to drive it 100 miles for it to run dry. Even with the 2X burn multiplier in the MA, that's still two whole sectors worth of driving. It would take well over an hour. Not many people are going to drive a GV for that long here...
