It’s common for people to add more gas even after the pump shuts off. Many round up to an even dollar and others will add more gas to go to the next dollar. This practice is called gas topping and we do not recommend it.
Is It Bad to Top Off Your Gas Tank?
Topping off your gas tank can negatively impact your car, the environment, and your wallet.
Although it is tempting to do, try and refrain from gas topping. Overfilling your gas tank can cause pressure to build in the tank and flood into the carbon filter vapor collection system, which is only meant for vapor. It can also affect your car’s charcoal canister. Gas in these systems can affect your car’s performance, damage the engine, and cause hundreds of dollars worth of damage.
When you top off your gas tank it can spill on the ground, and this causes harmful effects to the environment and other people’s health. If you damage your car’s vapor recovery system from topping off your gas, it won’t be able to effectively do its job of protecting people from the harmful vapors.
According to the Detroit Press, gas stations come with a vapor recovery system that – once the gas tank is full – will distribute gas vapors and gasoline from the pump back into the station’s tank to prevent vapors from escaping into the environment. Meaning, the gas you’re pumping into the tank that you’re paying for can end up being drawn back into the gas station’s storage tanks.
Be sure to keep this information in mind during your next gas station trip! As tempting as it may seem to try and round up, the risk isn’t worth the few extra miles you could get out of the fraction of gas you would be adding.