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If you're like many motorists in Wichita Falls, you turn on the air conditioning in your vehicle when temperatures soar.

But did you ever wonder if you could save on fuel by rolling down the windows instead?

Drivers across the country have been asking the same question for years, looking to cut down on how frequently they need to visit the pump. The truth is that the answer isn’t one-size-fits-all solution; it largely depends on your driving speed.

But let's take a look at why, what is better when, and thoughts regarding the science to reach this understanding.

The Crucial Switchover Point: Highway Speeds

Studies show that your driving speed plays a major role in determining which option is more fuel-efficient.

At city driving speeds, having your windows down uses less fuel than running the air conditioning. This is because at lower speeds, the drag caused by open windows is less significant. However, as you hit highway speeds, the scenario flips. The increased drag from open windows at high speeds requires your car to work harder, which burns more fuel. Therefore, at highway speeds, it's better for your fuel economy to roll up the windows and turn on the air conditioning.

This is the popular theory, but we didn't get here overnight.

The Experiments, Science, and Debates

The Society of Automotive Engineers

In 1990, Car Talk answered this question by referencing The Society of Automotive Engineers, which, at that time, found that the A/C was more efficient than having the window down, with the reason being window drag for why air conditioning is more efficient.

The Public's Radio references a different report from The Society of Automotive Engineers (presumably after the aforementioned one) in a 2020 article. In this report, they found that driving with the air conditioning on can lower fuel efficiency by up to 25% under certain conditions.

MythBusters

A 2004 MythBusters episode tried to settle the debate between rolling the windows down or using the air conditioning for better fuel efficiency. The episode was criticized for its scientific approach due to the test lacking control over variables that affect fuel efficiency, such as driving speed constancy in real world driving, environmental conditions, and the type of vehicle used. Critics were also upset after the initial experiment conducted in the the episode showed the vehicle getting worse fuel economy with the windows down. The team switched to a different experiment instead of continuing with the initial one.

Acknowledging the limitations and the criticism of their experiment, the MythBusters team revisited this topic in an episode that aired in 2012. This time, they made sure the vehicles were travelling at consistent speeds that reflected typical driving conditions for highway speeds versus city driving. They paid also paid closer attention to environmental factors that could influence the outcome.

Their findings showed that a switch-over point—the speed at which it becomes more fuel-efficient to use air conditioning rather than having the windows down—does exist at highway speeds due to increased drag from open windows.

Physics & Energy Professionals

Inside Energy took a look at the question and the opposite takes. In their article, they shared the thoughts of a physics professor and an engineer at the National Renewable Energy Laboratory (NREL). A 2002 analysis from NREL shows that, although A/C use has an impact on fuel economy, all light vehicles across the United States were using around 7 billion gallons of gas for air conditioning per year (that's roughly 5 and a half percent of total gas use). The consensus: there is a switchover point but knowing exactly what that number is will be difficult to know since there are multiple variables in addition to drag.

Other Considerations Beyond Fuel Economy

Now that this question is answered, it's time to look at some other considerations outside of fuel economy when it comes to using the A/C or windows.

Health & Comfort: While driving with the windows down might be the more fuel-efficient option at lower speeds, it's important to factor in the health and comfort of the driver and passengers, including pets. High temperatures can lead to heat-related health issues. This outweighs the fuel savings of driving with the windows down, particularly on hot days.

Safety: Higher speeds is when it's recommended to switch to air conditioning for fuel economy, but you should look at rolling up your windows before you reach those speeds for the purpose of safety. Driving at higher speeds with the windows rolled down can impact the safety of vehicle occupants in the event of an accident.

Tips for Keeping Your Vehicle Cool and Saving Fuel

Park in the Shade: When possible, park your car in the shade. This simple step can help reduce the interior temperature significantly, reducing the need to blast the air conditioning as soon as you start driving.

Use a Sunshade: A windshield sunshade can help keep your vehicle cooler when parked, making it less of a greenhouse and more of a comfortable ride when you return.

Vent Before Driving: If your car has been sitting in the sun, open all the doors for a minute or two before starting your drive. This helps to let the hot air out and cooler air in, reducing the initial load on your air conditioning.

Regular Maintenance: Ensure your vehicle’s air conditioning system is regularly maintained. A well-functioning system is more efficient and uses less fuel.

Consider Driving Times: If possible, avoid driving during the hottest part of the day. Early morning or late evening drives can be cooler, requiring less air conditioning.

The decision to use air conditioning versus lowering the windows will vary depending on the conditions. At lower speeds, you might save a bit on gas by keeping the windows down, but remember not to compromise on the well-being of yourself or your passengers. If everyone is good and you are looking to save while also keeping safety in mind, the best time to switch to air conditioning is when you're getting ready to shift to higher speeds.

And if you're running into any issues and need air conditioning repairs in Wichita Falls, Texas, contact us at North Texas Automotive Service.