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For about 85 percent of US vehicle owners, the answer is yes. The other 15 percent own luxury or high performance vehicles whose powerful yet delicate engines require the more expensive higher octane fuel.

According to a recent AAA study, American drivers waste more than $2.1 billion dollars a year using premium-grade gasoline in vehicles designed to run on regular fuel. It’s a mistake 16.5 million of us have made some 270 million times in the last 12 months. So if you used premium in a car, SUV, crossover, or small pick-up that doesn’t need it, you are in good company.

Simply, if your owner’s manual does not specifically require 93 octane in the tank, you are wasting money. You are – literally – pouring your money down the drain, or, in this case, your gas tank. Filling it up with additives your vehicle does not need.

Your vehicle will run just fine on 87 octane, which costs 20-50 cents less a gallon than premium. That adds up if you are the average driver who puts 15,000 miles on the odometer a year.

Premium sounds like a treat for your car, but it isn’t, says John Nielsen, AAA’s managing director of Automotive Engineering and Repair, explaining that higher octane is only higher octane, not higher quality. It doesn’t make your engine run cleaner, faster, or smoother. 

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For this octane study, AAA tested 87 octane (regular) and 93 octane (premium) gasoline in vehicles equipped with a V8, V6, or four-cylinder engines designed to operate on regular-grade fuel.

Each vehicle was tested with both fuels on a dynamometer, essentially a treadmill for cars designed to measure horsepower, fuel economy, and tailpipe emissions in a variety of driving conditions. The AAA laboratory testing found “no significant increases in any tested category.”

That’s corporate-speak for “you are wasting your money.”

“Premium gasoline is specifically formulated to be compatible with specific types of engine designs and most vehicles cannot take advantage of the higher octane rating,” says Megan McKernan, manager of the Automobile Club of Southern California’s Automotive Research Center, where the octane test was done.

[Read About Premium vs. Regular Gasoline]

AAA says seventy percent of U.S. drivers currently own a vehicle that requires regular gasoline, 14 percent own a vehicle that requires mid-grade gasoline (10 percent) or uses an alternative energy source (4 percent), and only 16 percent of vehicles require premium gasoline. 

The idea that premium is better for your engine may be a holdover from the days when drivers would buy a tank of premium once in a while, because it contained detergents to control carbon build-up. The idea was the detergents would act like the spin cycle on the washing machine and force out the dirt.

That may have been true in the days before power windows and anti-lock brakes, but now all gas grades have additives to protect engines while they control emissions and cut pollution. That’s a good thing.

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What’s not a good thing is that not all gasoline brands are the same. AAA says the gas at independent, low-price stations, may have fewer additives than what are described as “top tier” suppliers. 

“Drivers looking to upgrade to a higher quality fuel for their vehicle should save their money and select a top tier brand gasoline, not a higher-octane one,” says Nielson.

Previous AAA studies found that fuel quality varies significantly among gasoline retailers, and that using a better brand can result in 19 times fewer engine deposits, increase vehicle performance, and improve fuel economy.

Of course, you can also improve your fuel economy by observing these common sense tips you’ve heard hundreds of times, but always worth a reminder:

  • Slow down. According to the EPA, each 5 mph over 60 mph decreases fuel economy by up to seven percent.
  • Keep your tires properly inflated. Proper tire inflation can add up to 25 percent fuel economy. The flip side is improper inflation can cost you 25 percent fuel economy. Always use the pressure recommended by the vehicle manufacturer.
  • Change your air filter. A clogged filter can cost you 10 percent fuel economy.
  • Change the oil filter. Follow manufacturer recommendations
  • Get the junk out of the trunk. Using your car as an attic on wheels costs you approximately 13 gallons a year for every 100 pounds you drive around.