Yes, capping highway speed at 55 mph improves fuel economy

Cars use 50% of their energy overcoming aerodynamic drag. Reducing highway speed to 55 mph or less can improve fuel economy between six to eight miles per gallon.

GREENSBORO, N.C. — The gas price saga is stop-and-go. America slowly pumps the brakes on record-shattering prices but has faced road blocks rolling the burden to a stop.


Viewer Janice Sumner shared "tips from the experts."

One of the suggestions is, "Remember, every five miles above 55 miles per hour decreases fuel efficiency."

Is that true?



Yes, the gas hack claim is accurate. Going faster than 55 miles per hour noticeably reduces fuel economy. Drivers can save money if they slow down.


"That's absolutely true," affirmed Gas Buddy head petroleum analyst Patrick De Haan.

He explained, "(At high speeds) your vehicle is working harder to overcome drag. That's wind, right? It's every five miles you go up above that, you're losing a lot more efficiency. That's why 55 to 60 (miles per hour) is really the sweet spot. Your car is not having to work as hard against the wind...but generally, you're in a high gear at that speed, so you're in a perfect spot there and can get 400 miles out of a tank."

Consumer Reports also tested the claim. It measured gas mileage at a steady 55 miles per hour, 65 miles per hour and 75 miles per hour in both a standard car (Nissan Altima) and compact SUV (Toyota Rav-4). It found reducing speed from 65 to 55 improved fuel economy by six miles per gallon in the car and eight miles per gallon in the SUV.

"You don't have to go 70. You don't have to go what the speed limit says. There are minimums posted, but 55 to 60 is the sweet spot for most vehicles," De Haan said.

Be mindful, also, of what the car is carrying. Consumer Reports found at highway speeds, more than 50 percent of engine power goes to overcoming aerodynamic drag. Adding weight to that, even from an empty roof rack, slows down fuel economy.

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