High temperatures are scorching much of the United States, breaking records. But the thermometer isn't the only thing hitting record highs — so are the numbers on gas pumps.
And while you might want to seek relief in the air conditioning, blasting it in your car can use up gas for which you just paid a soaring price.
"If you're trying to save mileage, you're giving up a little bit of comfort," Steve Reinarts, automotive instructor at Dunwoody College of Technology in Minneapolis, told KARE.
Drivers might be looking to conserve fuel as they face higher prices at the pumps following Russia's invasion of Ukraine. As of June 16, the national average for a gallon of regular is up almost $2 per gallon compared with this time last year, according to AAA.
Using air conditioning can affect your car's fuel economy, according to the U.S. Department of Energy.
"Running your car's air conditioning is the main contributor to reduced fuel economy in hot weather," the department said on its website. "Its effect depends on a number of factors, such as the outside temperature, humidity and intensity of the sun. Under very hot conditions, A/C use can reduce a conventional vehicle's fuel economy by more than 25%, particularly on short trips."
Does opening windows help?
So how can you get a break from the heat without also breaking the bank? One of the most debated topics is whether you can save gas by simply opening the windows.
Alas, it's not as simple at it might seem. In fact, experts say that having open windows while traveling at highway speeds can reduce fuel economy even more than running the A/C.
Part of the design process of modern cars involves tests in wind tunnels. Cars are the most aerodynamic — meaning air slides over them with the least resistance — when the windows are closed.
"Rolling down your windows instead of using A/C causes aerodynamic drag," AAA said in an e-mail. "In many cases, this increase in drag at highway speeds negates any savings on engine load from not using A/C."
The energy department sounded a similar note in a 2015 online post: "Because having the windows down increases wind resistance, it's not very efficient at highway speeds. When rolling down the freeway, it's best to turn on the air conditioning at a temperature that keeps you comfortable, but not cold."
But what about when you're not cruising through the countryside at 70 miles per hour? If you're sitting in stop-and-go traffic during rush hour, is leaving the windows closed and cranking up the A/C still cheaper?
Experts say no. At slower speeds, the engine has to run faster than it otherwise would to power the air conditioning. At that point, it makes the most sense to open the windows for relief.
"At lower speeds driving around town, rolling down the windows is the most efficient choice," the energy department said.
Returning to what Reinarts said, keep in mind that this advice is based on what saves the most gas, not what cools off the car and its passengers best. If you climb into a car that has been baking in the sun all afternoon, experts say that you might want to consider running the A/C for a few minutes to break the heat, then turn it off and open the windows to cut gas consumption.
Here are some other tips from experts:
• When starting a trip in a hot car, open the windows a couple of inches to help the air conditioning push out the hot air.
• Park your car in the shade or use a windshield shade to block out the sun.
• Reduce the amount of time you spend idling with the air conditioning on.
• Consider getting a car that's a lighter color or has tinted windows.
• Follow other advice for maintaining your car's efficiency, including staying up to date on vehicle maintenance, using cruise control and combining trips when possible (go the supermarket and the hardware store on the same trip rather than making separate ones).
