It’s a question that is becoming increasingly relevant, considering that climate scientists are now saying 2024 will top 2023 as the hottest year on record. Are you consuming more fuel by running your car’s air conditioning unit than if you drove with the windows down?
It’s also a question that the content creators at AccurateAuto (@accurateautoinc), a mechanic shop in Northglenn, Colorado, took to TikTok. The Nov. 5 video asking several mechanics has gotten more than 265,000 views as of Monday.
At first, a pair of mechanics field the question. One maintains, “It consumes more fuel, but above a certain speed, you’ll save gas using the A/C rather than rolling the windows down.”
Another said, “Not necessarily.”
Yet another interviewee was equivocal, saying, “People say yes and no,” before taking the stance that it’s a “myth.”
The last person interviewed pointed out, “So, it uses your A/C compressor, which puts more load on the engine, so it can. Better to use it while cruising than when you’re in stop-and-go traffic.”
Other opinions on the matter
A Consumer Reports article from 2017, referenced on several mechanics’ websites, had a more definitive answer:
“We’ve tested this at various temperatures with multiple vehicles,” says Jake Fisher, CR’s director of auto testing. “We found that on an 85-degree day, running the A/C can reduce fuel economy by 1 to 4 mpg, depending on the car. But air conditioning dehumidifies the car’s interior, which can help keep the driver alert and safe. We think that’s a worthwhile trade-off.”
Fisher also remarked that “the effect of opening the windows at 65 mph did not measurably reduce fuel economy,” poking a hole in at least one AccurateAuto assessment.
Redditors also took the question on in a post to r/cars in 2021.
“I think there was a MythBusters episode about this,” one said. “Your AC puts a load on the engine, and the windows down produce more drag. The conclusion was it was actually more fuel efficient to have the AC on than to have your windows down at highway speeds. The most fuel efficient would be to have windows up and AC off.”
That person continued, “Of course this will vary depending on car, but generally I find the effect to be pretty minimal in a modern car unless you are trying to hypermile. Your driving style has more of an effect than the windows or AC.”
Another shared, “From experience I can attest old cars with less horsepower take a much harder hit. I daily an old VW rabbit, without AC I get 42.5mpg but with AC it drops to under 35mpg and the car struggles to maintain speed.. The whole AC system is new not an issue, but the main cause is the car is rated with a 48hp engine lol.”
Commenters provide perspective
Of course, since this arrived on TikTok and went viral, commenters were eager to share their views.
“I have driven Toyota, Honda, Mercedes Benz and I can boldly tell you it does, my friend,” said one.
@accurateautoinc Replying to @Grizzlystaircase Does A/C WASTE Gas?! 🤔🚗#mechanic #autoshop #car #cars #truck #diesel #automobile #auto #cartok ♬ original sound – AccurateAuto
Another asserted, “There’s no free energy. It is impossible for A/C to not consume more fuel. otherwise there would be home AC units that used no electricity.”
“Depends on what you mean by waste,” one pointed out. “If it’s 100 degrees, it’s not wasting anything. It’s needed lol.”
The Daily Dot has reached out to AccurateAuto via TikTok and Instagram direct message.
Internet culture is chaotic—but we’ll break it down for you in one daily email. Sign up for the Daily Dot’s web_crawlr newsletter here. You’ll get the best (and worst) of the internet straight into your inbox.
