No, premium gas won’t save you money by making your car more fuel efficient

With national gas prices still above $4 a gallon, many drivers are looking for ways to save on fuel wherever they can.

Some have wondered whether one way might be to try splurging on “premium” gas, in the hopes that it causes their car to perform more efficiently, thus cutting costs in the long run. Google search data shows people are searching for "premium gas mileage vs. regular," and that searches related to premium gas spiked as prices rose following the Russian invasion of Ukraine.

THE QUESTION

Can I save money by using premium gas to improve my fuel efficiency?

THE SOURCES

• Federal Trade Commission
• Consumer Reports
• Meineke
• Department of Energy
• Study conducted for the Department of Energy
• U.S. Energy Information Administration
• Greg Brannon, AAA Director of Automotive Engineering and Industry Relations

THE ANSWER

No, premium gas won’t save you money by making your car more fuel efficient.

WHAT WE FOUND

Premium gas refers to gas with higher octane levels. High-octane gas is more stable than low-octane gas, meaning it’s less likely to spontaneously combust without a spark and cause “engine knocking,” when fuel burns unevenly causing abnormal pressure in the engine, which can cause damage or performance issues.

High-performance engines like those found in sports cars sometimes require high-octane gas. That’s because the higher-stress environment inside the engine can create conditions more prone to knocking.

However, most modern cars have computerized devices that prevent engine knocking, making it a relatively rare problem for drivers of everyday cars.

As a result, experts advise against purchasing premium gas unless your car’s user manual recommends or requires it.

“On its own, paying for premium gasoline does not make your car run better or get greater gas mileage,” reads a blog post from auto repair company Meineke. “Higher octane gasoline reduces knocks and pings in high-pressure environments, which exert more energy and burn fuel quicker. If your car manual doesn’t require you to use high octane fuel, using it anyway probably won’t help.”

The Federal Trade Commission recommends regular gasoline for most cars, saying premium rarely provides mileage or performance benefits.

“In most cases, using a higher octane gasoline than your owner’s manual recommends offers absolutely no benefit. It won’t make your car perform better, go faster, get better mileage or run cleaner,” reads one advice pamphlet from the FTC.

For most drivers, the choice is simple: Use premium if your car requires it, and regular if it does not. But some manuals say premium gas is “recommended” but not required.

Greg Brannon, an automotive research expert with AAA, says for those drivers, whether or not it makes sense to splurge for premium depends on how they’re using their vehicle, but improved gas mileage is not really a factor.

“If you're using premium fuel in a car that recommends premium, our research found that it could improve horsepower and fuel economy, but only by about three percent. That's a very small difference,” he told VERIFY. “If you're a racer, and you're looking for every last hundredth of a second on the track, that's one thing, but most of us are just driving to work. If your car recommends premium, you are 100% fine to use regular fuel in most situations. Otherwise, the extra cost for that fuel is just going right out the tailpipe.”

So, even in cars that could have a slight efficiency improvement by using premium gas, that would only become cost savings in a world where premium gas costs less than 3% more than regular. Right now, it’s nearly 19% more.

One study, conducted for the Department of Energy and sponsored by corn growers (ethanol is used as an additive to increase octane levels), ran multiple cars through multiple conditions. In some tests, higher octane gas actually resulted in slightly decreased fuel efficiency. In most, there was a slight improvement or no difference at all. 

A Ford F150 placed in a high-stress test recorded 17.6 miles per gallon using low-octane gas. With high-octane gas that improved to 18 miles per gallon.

But looking at current fuel prices and doing some math, we can see that the benefit does not offset the premium price.

With regular gas averaging $4.066 per gallon, according to the EIA, a dollar’s worth of regular would take you 4.33 miles in the F150. A dollar of premium would only get you 3.73 miles at the current average price of $4.831 per gallon.

That means even in conditions optimized to increase the performance benefits of premium gas, it still won’t save you money.

“For most vehicles, higher octane fuel may improve performance and gas mileage… by a few percent during severe duty operation, such as towing a trailer or carrying heavy loads, especially in hot weather,” says a Department of Energy website. “However, under normal driving conditions, you may get little to no benefit… The cost increase is typically higher than the fuel savings.”

Consumer Reports also conducted a test comparing the effects of octane levels on fuel efficiency for a pair of everyday cars, and found no noticeable difference.

“The fuel economy was exactly the same running these two cars on regular fuel as we did when we ran them on premium fuel,” Consumer Reports’s Mike Monticello said in a video.