http://www.alternativefuelstips.com

A mistake that many drivers make when filling their gas tank is to overfill it by topping it off. When the gas pump nozzle clicks off automatically, do you keep pumping? Most gas stations are equipped with pumps that have vapor recovery systems to recover gas vapors keeping those vapors from getting into the air. If you top off your tank it will cause you to pay for gas that is drawn back into the gas station's vapor recovery system. When you overfill your gas tank it is almost a certainty that gasoline will evaporate or will be spilled. If either of these or both of these occur it means buying gas that is not getting into your car. That has to hurt you in the wallet.

http://www.alternativefuelstips.com