Improving Gas Mileage on Summer Road Trips

These percentages vary in direct proportion to the duration of the road trip and the decibel level of the sounds emitted by the offspring in the back seat.

by Adriane Jaynes

Summer is here! I don’t know about you, but for my family that means road trips. Lots and lots of road trips… Even though gas prices are lower this year than they have been in a while, it is still important to drive efficiently to try to minimize negative impacts on the environment and air quality.

Though car engines typically run more efficiently in warmer temperatures, increased use of air conditioning (AC) can actually reduce fuel economy by as much as 25%, resulting in worse gas mileage in the summer heat, which can really add up and unnecessarily increase your gas budget.

Having lived in southern states my whole life, I would never suggest that anyone go any significant length of time in the summer with the AC off,

but the following tips can help improve your gas mileage, allowing cheaper gas to take you even farther!

  • Actively manage the car-engine-factAC.
    • When possible, park your vehicle in the shade and use a sunshade in your windshield to avoid turning your car into a solar oven.
    • If the car is too hot, lower the windows to vent the hot air for the first few minutes, and then switch to using the AC.
    • When driving at high speeds, use the AC instead of rolling down the windows.
    • When the AC is on, if possible, avoid using the “max” setting for extended periods.
  • Avoid idling!
    • Some people insist that idling is better than turning the car on and off multiple times – this is a myth. In modern cars, after 10 seconds of idling, you burn more fuel than if you turn your car off and then turn it back on. Don’t believe me? Just watch this informative video!
    • Unless you have mobility issues or have multiple small children in the car, skip the drive-through; park your car and go inside!
  • Use cruise control while driving on highways to maintain a consistent speed and conserve fuel.
    • Sometimes on hills, cruise control can be less efficient. Watch your RPMs to see how hard your engine is working and make adjustments as needed.
  • Remove any unnecessary weight from the vehicle. Each 100 pounds of extra weight in your vehicle can reduce fuel economy by 1%. Note: Different family members tend to have different definitions of “necessary” items when packing the family car. If the necessity of the item in question is related to the sleep, nourishment, transport or entertainment of young children, your wife is probably right—it is necessary.
  • Avoid transporting cargo on the rooftop of the vehicle.
    • Traveling with cargo on the roof increases wind resistance and can significantly lower fuel economy.
    • If you can’t fit everything inside the car, rear-mounted cargo has a much smaller effect on fuel economy than rooftop cargo… and you’ll look less like the Griswolds on their way to Wally World!
  • Check your tire pressure.
    • Underinflated tires can reduce fuel economy by 3% for every one pound per square inch (PSI) drop in pressure in all the tires.
    • Having tires inflated to the proper pressure is also safer and can help tires last longer, saving you money on gas and tires. This also makes you less likely to have a tire blow out and get stuck on the side of the road in the middle of nowhere.
  • Avoid aggressive driving.
    • Aggressive driving (speeding, quick acceleration and heavy braking) can reduce fuel economy by as much as 33% at highway speeds and 5% at city speeds.
    • This video from a very old episode of PBS’s MotorWeek, features one of my bosses mildly swearing and shows real-world effects of aggressive driving on fuel economy. Not shown in this video are the arguments which can ensue inside the vehicle when the driver is making bad choices. In my experience, aggressive driving can increase the interpersonal stress among front seat passengers anywhere from 5%-200%. These percentages vary in direct proportion to the duration of the road trip and the decibel level of the sounds emitted by the offspring in the back seat.

Of course, let’s not forget our in-town driving can be reduced by combining trips, walking, biking, and taking the bus.  If your summer travels take you to a city with more mass transit options, don’t be afraid to explore a new city like the locals! Most mass transit systems in large cities are very user-friendly. Skip the rental car or taxi and save tons of money by using the subway, bus, or a bike share program. I’ve used all three in my travels around the country and around the world, even traveling with young children, and mass transit is my preferred way to get around a large city.

For more information on how to improve your fuel economy, check out the following sites:

Looking to replace your car? Start your search at to view side-by-side, customized comparisons of costs associated with owning and operating different makes and models of both traditional and alternative fuel vehicles.

*Adapted from Clean Cities Technical Response Service Team, Question of the Month, May 2015

Adriane Jaynes is the Energy Programs Coordinator at INCOG, where she manages the Tulsa Area Clean Cities Coalition, which promotes voluntary projects to increase the use of alternative fuel vehicles by focusing on projects designed to reduce overall operating costs and increase public access to new fuel sources. Additionally, she is a wife, mother, and family road trip master.

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