Whenever you fill your car with gasoline, always fill it all the way up. By doing so, you'll make fewer trips to the gas station and increase the fuel efficiency of your car. Also, when the pump clicks off automatically when your car's tank is full, don't remove the pump right away. There is about one-fourth cup of gasoline still in the hose line (that you paid for) that needs to work its way into your gas tank. If you wait about 15 seconds, you'll get every last drop.