For esthetic and other reasons, many automotive vehicles are designed so that the rear license plate functions as a door which covers the fuel tank cap. In other cases a separate door is used for the same purpose, and like the license plate door, it is spring biased into a closed position over the tank cap. With both of these designs the door must be held against the force of the return spring while the fuel tank is being filled. Not only is this inconvenient but it frequently results in spillage of fuel when the tank is being filled.