Premium Gas: What It Really Does for Your Car and When You Need It

When you see premium gas, a higher-octane fuel designed for engines that need it to prevent knocking and maintain performance. Also known as high-octane fuel, it’s not a magic upgrade—it’s a specific requirement for certain engines. Most cars don’t need it. Your owner’s manual will tell you if your engine actually requires it. If it says "regular recommended," then premium gas won’t make your car faster, cleaner, or last longer. It just costs more.

Engine knocking—those pinging or rattling sounds under acceleration—is the real reason premium gas exists. It happens when fuel ignites too early in the cylinder. Higher octane rating, a measure of a fuel’s resistance to premature combustion under pressure means the fuel can handle more compression without exploding at the wrong time. High-performance engines, turbocharged models, and some luxury cars are built with higher compression ratios. They need that extra resistance. But if your car runs fine on regular, switching to premium won’t fix a rough idle or improve fuel efficiency, how far your car travels per gallon of fuel. A 2018 Honda Civic or Toyota Corolla won’t suddenly become a sports car because you filled up with 93-octane instead of 87.

Some drivers think premium gas cleans engines better. It doesn’t. All gasoline sold in the U.S. has detergent additives required by the EPA. The difference between regular and premium isn’t in cleaning power—it’s in how the fuel behaves under heat and pressure. If your car’s manual doesn’t call for premium, you’re not protecting your engine—you’re paying extra for something your engine doesn’t use. And if your car does need it? Skipping premium can cause long-term damage. That’s not a myth. It’s engineering.

There are exceptions. Some older cars with high-mileage engines might run better on premium after years of carbon buildup. But that’s not because premium cleans—it’s because the higher octane reduces knocking caused by worn components. It’s a temporary fix, not a solution. And if you’re driving a 2018 car with a turbocharged engine, like a Subaru WRX or a BMW 3 Series, then premium isn’t optional. It’s part of the design. Ignore it, and you risk engine damage or reduced power.

So what should you do? Check your manual. Look at the fuel door. If it says "Premium Unleaded Required," use it. If it says "Premium Recommended," you can use regular—but you might lose a little power or get a bit less smooth acceleration. If it says "Regular Recommended," stick with it. No savings. No gain. Just extra cash at the pump.

Below, you’ll find real-world advice on how premium gas interacts with engine design, when upgrades like fuel injectors or tuning make a difference, and what other drivers actually experience when they switch—or don’t. No guesses. No marketing. Just what works.