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Topping Off: Should You or Shouldn’t You?

Tempe Auto Repair Visiting the gas station to fuel up is an activity almost no one enjoys. As a result, many ideas and strategies have been formed to reduce the visit to a gas station, whether they work or not is an entirely different can of worms. One of the most popular strategies is topping off at the gas pump. While it sounds practical, unsuspecting car owners may be causing more harm than good by trying to ‘cheat’ the gas pump.

Will My Car Take in More Gas After the Initial Nozzle Click?

The short answer: Yes. The longer answer: Yes, but here’s why: Your car is capable of admitting more gas after the first automatic nozzle click. The nozzle itself is controlled by a vacuum system which senses when it’s time to off the flow of the fuel. If you were to inspect the fuel nozzle closely, you might see a small port or hole at the tip, which is responsible for relieving some of the air that is trapped in your gas tank. Once the fuel flow stops, this trapped air is permitted to escape through this tiny hole which makes more room for more fuel. Every modern fuel pump operates by a vapor recovery system that operates by recovering any fuel vapors that may exist in your gas tank. The vapor recovery system will not replace any of the valuable fuel inside your tank, but it will return the fuel vapor to the storage tank. While it’s possible to get a couple more drops of fuel from this trick, don’t get too carried away. Overfilling the tank can have disastrous consequences.

Topping Off: Potentially Causing More Harm Than Good

The gas nozzle will automatically click when your tank is full. If you continue to try and pump more gas, the following may result: + You may not receive the additional gas, instead you’ll be paying for gas that the next person behind you gets instead. + You run the risk of overflowing the gas tank which can lead to not only damage to your car's paint, but hazardous puddles that are flammable and dangerous. + Topping off could lead to excess fuel entering your car’s vapor recovery system which could damage it. This may result in your check engine light coming on. Your fuel system is responsible for absorbing gas continuously, but the seal where your filler meets the chassis may erode under constant saturation. + The temperature outside of the car may influence whether there is extra room in your gas tank. During a hot summer day, the extra room in your gas tank is needed for when gasoline will expand. Topping off will force the excessive fuel to collect in your vapor recovery system. Instead of partaking in this harmful practice, consider the following tips to save gas: + Be sure to choose the right grade of gasoline for your vehicle - Most vehicles are completely capable of running on regular gasoline. If you’re ever in doubt, consult your owner’s manual to see what's right for your car. Avoid topping off at the pump and don’t forget to replace the fuel cap when you’re finished pumping gas. + Find the best gas deals, local to you - This may be difficult to do if you live in a popular city or when prices are at an all-time high. Try and find a gas station that offers steady low prices and make it a habit to go to only that gas station if you can help it. Install and use an app like GasBuddy to find the best prices for gas near you. + Try carpooling - See if there’s a car pooling practice at your work or if you could generate interest in carpooling. + Avoid aggressive driving - Driving above the speed limit or aggressively not only eats away at your gas, but can also result in an accident. You should drive with the goal of having smooth starts and stops. Instead of being the first one to take off from a stop light, ease into acceleration. Even if everyone around you is stomping on the gas pedal. + Improve the aerodynamics of your car - While it may be tempting to install a roof rack (extra travel space), you’re creating more air friction which will cause the car to have to work harder to accelerate or maintain acceleration. If you can help it, remove the roof rack and carry the luggage inside your vehicle. Better yet, remove any excessive weight you don’t need. + Minimize vehicle idling - Most modern vehicles are now capable of warming up in 30 seconds or less. Gone are the days when your vehicle needs to idle for 25 minutes before you can rush off to where you need to go. + Keep up on vehicle maintenance - Maintaining your vehicle’s maintenance not only results in better performance, but you may also see an improvement in your fuel economy. Neglecting your air filters and even the condition of your tires could contribute to over 13% of your fuel costs.


Topping off is a common practice used today, but many unsuspecting car owners aren't aware of the potential damage they could be causing to their vehicles. Instead, rely on time proven tips to improve your fuel economy. Book An Appointment
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