We had a rental car that had full electrical (?) failure. My husband had me call the rental place and try to find the closest rental agency that we could bring the car to and exchange it for another car. He couldn't stop the car, because once he did, he knew he'd never get it started again and then we'd have to wait for a tow. He managed to get it to one of their rental agencies, at an airport, to drop it off. When we went to the counter, they said that we owed this big fee because we hadn't filled up the tank before dropping it off. It took my husband considerable arguing with her to convince her that we'd *saved* them money--if we'd stopped to get gas and turned off the engine, it wouldn't have started again and we'd have needed a tow truck, which would have cost them a lot more than needing to refill the gas tank themselves! She finally gave in, but she just did *not* seem to get that electrical failure=car keeps running, but once you stop it it probably won't start up again.