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How many of us wait until the in-dash fuel gauge approaches empty before filling the gas tank? And how many of us allow the gauge to hover on empty for several more miles before refueling?

We rely on in-dash fuel economy displays to estimate the number of miles per gallon our vehicles can get, including the number of “miles to empty.” But AAA-assisted research shows that the accuracy of these systems varies over shorter trips, or it hinges on the consistency of other factors that determine gas mileage, such as speed and acceleration.

This means we could risk running out of gas. A consumer survey conducted by AAA shows that 74% of drivers refer to their miles-to-empty display when they’re low on gas to help them decide when to refuel.

 To avoid running out of gas, AAA recommends minding the gas gauge and refueling when it drops to a quarter tank.

Driving habits directly impact fuel economy.

We all want to get the most from our gas tanks, especially when fuel prices rise. However, a closer look at different driving scenarios showed significant variation based on changes in speed, acceleration and distance.

AAA worked with the Automotive Research Center (ARC) of the Automobile Club of Southern California to test select vehicles. Using a series of simulated driving scenarios, researchers determined the accuracy of the vehicles’ miles-to-empty displays. Different driving situations included sitting in traffic, typical in-town driving and highway driving.

Results suggested that different vehicles responded differently to changes in driving and that driving style and conditions can affect the accuracy of their miles-to-empty systems. While testing revealed irregularities, researchers say the fuel economy display can still be a helpful tool. The information it shows can help you see how your driving habits influence fuel economy. It’s recommended that drivers reset their vehicle’s trip data after filling up the gas tank and then observe how the fuel economy display changes with driving conditions.

AAADrive helps Members drive more smoothly and monitor speed. Get it in the AAA Mobile App.

Learn More

Now that you know you can’t always count on your fuel gauge, here are six ways to maximize your fuel economy:

  • Plan and consolidate trips. Run multiple errands per trip and plan trips for those times when traffic is lighter.
  • Use the most fuel-efficient vehicle. If you have more than one car, drive the one that’s most efficient when you can.
  • Don’t accelerate aggressively. Also, make sure you keep your tires at the recommended tire pressure (which can be found inside the driver’s side door or in the owner’s manual). Learn more.
  • Jettison unused or heavy items. Use roof racks sparingly and take special carriers off your vehicle when you’re not using them. Such items will reduce the fuel economy of smaller cars especially, compared to larger vehicles designed to haul more weight. Added items can cause a vehicle to drag, which impacts the aerodynamics of a vehicle’s design.
  • Use less AC. Opt for fresh air to save fuel. Open windows don’t affect fuel economy as much as the engine power needed to run the air conditioner—even at highway speeds.
  • Seek shade. When it’s hot out, find a shady parking spot or put a windshield screen in your car to help keep the car’s interior cooler. This can help reduce the need for air conditioning—and the fuel consumption to power it.

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