Summer Driving Tips to Help Cut Your Fuel Costs

CHICAGO, June 19, 2015 – Whether you are taking a road trip this summer or just running errands around town, there are steps you can take to improve your fuel economy and save money on fuel in the summertime.

Chicago Area Clean Cities, a nonprofit coalition focused on promoting cleaner energy for business and municipal fleets in Chicago and the surrounding suburbs, encourages consumers to evaluate ways that they can improve their fuel efficiency.

Hot weather can actually increase a vehicle’s fuel efficiency, according to the U.S. Department of Energy’s website Engines warm up to efficient temperatures faster; summer grades of gasoline can have slightly more energy; and warm air causes less aerodynamic drag than cold air. On the other hand, keeping passengers comfortable in hot weather by rolling down the windows or using the air conditioning (AC) can reduce fuel efficiency.

Running your car’s AC is the main contributor to reduced fuel efficiency in hot weather, according to studies conducted by the Society of Automotive Engineers (SAE). The effect that AC has on efficiency depends on a number of factors, such as the outside temperature, humidity, and intensity of the sun. Under very hot conditions, AC use can reduce a conventional vehicle’s fuel efficiency by more than 25 percent. AC’s effect on hybrids, plug-in hybrids (PEVs), and electric vehicles (EVs) can be even greater on a percentage basis.

According to, driving with your windows down can also reduce fuel efficiency. Open windows increase aerodynamic drag (wind resistance), making your vehicle use more energy to push through the air. While this effect is quite small at low speeds, it increases at highway speeds.

Chicago Area Clean Cities offers the following tips to help drivers use their AC more efficiently, and therefore improve fuel efficiency in the summer while staying cool:

  • Read your owner’s manual for detailed information on how your vehicle’s AC system works and how to use it efficiently.
  • Park your vehicle in shady areas or use a sunshade to keep the interior from getting too hot.
  • Do not use the AC more than needed or set the temperature lower than needed.
  • If you are driving at high speeds, use the AC instead of rolling down the windows. If the vehicle is too hot, you may lower the car windows to release hot air for the first few minutes. Once the hot air has left the vehicle, switch to using the AC.
  • Avoid excessive idling. Idling can use a quarter to half a gallon of fuel per hour, and even more if the AC is on. Do not idle the vehicle to cool it down before a trip; most AC systems actually cool the vehicle faster while driving.
  • PEV owners should pre-cool their vehicles with the AC while still plugged in. Since PEVs use battery power to provide AC, it can drain the vehicle’s batteries and reduce the vehicle’s overall range. If you need to use the AC to cool down your PEV, try to do so while the vehicle is still charging.

The following tips can be used year-round to improve fuel efficiency:

  • Use cruise control while driving on highways to maintain a consistent speed and conserve fuel.
  • Remove any unnecessary weight from the vehicle. Vehicles with heavier loads tend to have reduced fuel economy. An additional 100 pounds in your vehicle can reduce fuel economy by one percent.
  • Avoid transporting cargo on the rooftop of the vehicle. Traveling with cargo on the roof increases wind resistance and can significantly lower a vehicle’s fuel efficiency. Rear-mounted cargo has a much smaller effect on fuel economy than rooftop cargo.
  • Avoid aggressive driving. Aggressive driving (speeding, quick acceleration and heavy braking) can reduce fuel economy by as much as 33 percent at highway speeds and 5 percent at city speeds. This informational video shows real-world effects of aggressive driving on fuel economy.
  • Ensure your tires are properly inflated. Tires that are not inflated to the proper pressure can reduce fuel economy by 0.3 percent for every one-pound per square inch (PSI) drop in pressure in all of the tires. Having your tires inflated to the proper pressure is also safer and can help tires last longer.
  • Pay attention to the speed limit. Not only is this a safe practice, but also gas mileage tends to decrease when driving at speeds above 50 miles per hour.

For more information on improving your fuel efficiency, go to the following websites:

  • Fuel Economy in Hot Weather
  • Gas Mileage Tips

About Chicago Area Clean Cities
Chicago Area Clean Cities (CACC) is a 501(c)3 nonprofit coalition focused on promoting cleaner energy for transportation and automotive fleets in Chicago and the surrounding suburbs. CACC is one of nearly 100 coalitions across the country that are affiliated with the U.S. Department of Energy’s Clean Cities program, which brings together stakeholders to increase the use of alternative fuel and advanced-vehicle technologies, reduce idling, improve fuel economy and air quality. CACC concentrates its efforts on educating businesses and municipalities in the six-county Chicago area, including Cook, DuPage, Kane, Lake, McHenry and Will counties. To become involved or learn more about the coalition visit

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