Premium Fuel Is a Waste in Cars That Don't Need It, Consumer Reports' Tests Show

Despite these findings, many drivers continue to put premium fuel in cars when it’s only been recommended. 

When a May 2026 nationally representative Consumer Reports survey asked about fuel use in their personal vehicles, we found that 20 percent of people in the U.S. who drove gas-powered vehicles used midgrade or premium gas. Only about a quarter of them said they did so because it was required. They were more likely to say they used midgrade or premium gas because it was recommended for their vehicle (31 percent); because they thought the vehicle performed better than with regular gasoline (also 31 percent); and because they thought it was better for the engine than regular gasoline (30 percent).

To empty the cars of any premium gas that could be in the fuel system, we drove them nearly dry, then ran through a full tank of regular gas before we started testing.

All tests were conducted according to Consumer Reports’ stringent fuel-economy protocol, with fuel consumption measured using an inline fuel meter installed by our technicians.

Both SUVs achieved the same fuel economy when tested with regular fuel and with premium fuel. During this testing, the cars felt and sounded the same; we didn’t experience any engine pinging or knocking noise when using regular fuel.

The owner’s manuals say that drivers might notice a decrease in performance when the vehicle is running on regular gas, but our test results showed otherwise. Using a GPS-based device connected to a computer that logs data, we found that each SUV got an identical 0-to-60-mph acceleration time regardless of whether we filled it with regular or premium gas: 9.7 seconds for the Acura and 6.3 seconds for the Nissan.

“While we saw similar performance, it is possible that there can be some difference under extreme conditions, like very high heat or heavy towing,” Fisher says. As with any car, if your engine knocks, you should switch to a higher-octane fuel. If we were towing with the Armada, we would follow the manufacturer’s recommendation and fill up with 91 or higher.

The results were the same as we saw a decade ago, when we did similar tests on a 2015 Acura TLX sedan with a four-cylinder engine and a 2016 Nissan Maxima sedan with a V6 engine. They also mirror what we saw in 1995 when we did similar tests on a Dodge Dakota pickup. In fact, when Consumer Reports first started publishing in 1936, we told drivers to buy the cheapest gasoline their car would run on without it knocking or pinging.

All gas comes with octane additives to prevent an engine from knocking. In the U.S. and Canada, fuel is differentiated by an Anti-Knock Index (AKI) octane rating, sometimes listed as (R+M)/2, which measures a fuel’s resistance to engine knock. (Some owner’s manuals and fuel filler doors will also list an RON number, which is used outside North America.) Most gas stations sell three grades of gas: regular (87 octane), midgrade or plus (89), and premium (91-93). In high-elevation states, 85 octane gasoline is also sold, and some gas stations sell 94 octane premium.

The higher the octane rating, the more expensive the fuel. “The simplest reason why is because premium fuel requires additional processing than just regular fuel,” says David Bennett, senior automotive manager at AAA.

Some high-performance cars require premium fuel because the automaker assumes that the engine will be put under stress, which increases the risk of knock. In some cases, automakers require premium fuel because they’re squeezing a lot of power out of a smaller engine. “As you reduce the size of the engine and introduce turbocharging, knock becomes increasingly more of a problem,” says Giorgio Rizzoni, director of the Center for Automotive Research at Ohio State University.

Check your car’s owner’s manual or fuel filler door to find out what kind of fuel the manufacturer says you should use. If it says that premium is recommended, it’s safe to use 87 for daily driving. Sometimes the owner’s manual will tell you when to use premium (such as when towing or in extreme heat) and when regular will suffice.

But if your car indicates that premium is required, it means the manufacturer designed the engine to operate on a high-octane fuel. If you use regular, you risk excess engine wear and might void any remaining manufacturer’s warranty.

“There’s a big difference between the words ‘recommended’ and ‘required,’” says CR’s Jake Fisher.

In addition, high-mileage or older engines may experience knocking due to carbon buildup. If you drive an older vehicle and start to hear a knocking or pinging sound, try filling up with premium.

“There are some older engines that could benefit from higher-octane fuels to prevent knocks due to carbon buildup,” says John Ibbotson, chief mechanic at the Consumer Reports Auto Test Center.

To prevent carbon buildup, look for Top Tier detergent gasolines. These contain detergents that help prevent carbon buildup in the engine, which can also hurt performance and reduce fuel economy, according to an AAA study. Most oil companies you’ve heard of are Top Tier—BP, Costco, Chevron, ExxonMobil, Shell—but check toptiergas.com for a full list. Switching to Top Tier gas regularly can reduce existing carbon buildup, based on AAA tests. Many automakers, including Acura, specifically endorse it.