When pumping gas, save money and maximize fuel by doing one thing: Hold the gas pump correctly. When you hold the gas trigger all the way down, it is the fastest way to fuel up your car. But it also creates the largest amount of gas vapors, which means the fuel going into your gas tank becomes vapor and then it's returned back into the underground storage tank at the station. You end up with less fuel, still paying the same price. To maximize your fuel efficiency, pump gas at a slower speed to minimize vapors and waste.