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Buying a Car: Do You Need to Use Premium Gas?


Buying a car often involves a lot of research, and sometimes it will reveal that the vehicle you want requires premium fuel. You might be faced with a big disappointment since premium gas often costs an additional 50 cents or more per gallon than regular. Add in overall higher gas prices, and it could be a deal-breaker.

Can you buy the car anyway and skip the premium gas? We have the answer.

What is Premium Gas?

A discussion of whether you need to use premium fuel begins with an explanation of exactly how premium fuel differs from regular gas.

Many drivers think premium fuel is more refined than regular or that it’s cleaner, but that’s not the case. It’s simply less combustible than regular gas. What exactly does that mean?

We’ll spare you the mechanical details. But the critical thing to remember is that engines running on less combustible fuel are less likely to experience pre-ignition than powertrains that run on more combustible regular gas. Pre-ignition leads to engine knocking. You can sometimes hear it in older cars or high-performance vehicles that require premium gas and instead were filled up with a tank full of regular.

Too much engine knocking can cause damage. It means that your engine isn’t running very well, which isn’t something you want to deal with after buying a car.

RELATED STORIES: Ways to Get Better Gas Mileage Out of Your Car

Can You Put Premium Gas in Any Car?

Considering that premium fuel prevents engine knocking, why don’t all cars take premium? The answer lies in the engine’s construction.

A typical car doesn’t need a high-performance engine because its engine uses a simple design with a low compression ratio that runs just fine on regular gas. However, most high-performance or luxury cars bring more power and a higher compression ratio, which means their engines are more prone to pre-ignition when using the wrong type of fuel.

“If you’re looking to save money at the pump, make sure you’re not buying the pricier premium fuel for no reason,” said Autotrader’s Executive Editor Brian Moody. “Your owner’s manual should tell you whether you MUST use premium fuel or if it’s just ‘recommended.’ Keep in mind, cars that ‘require’ premium fuel perform best and get their best fuel economy when you stick with the required octane rating.”

Do You Have to Use Premium Fuel?

So you need to use premium fuel in a luxury car, right? Most luxury vehicles provide engine-knock sensors, which means that they won’t allow the engine to knock, even if you put in the wrong type of fuel. Avoiding engine knock prevents engine damage, so your engine will likely run just fine even if you put in regular rather than premium.

Still, if your engine isn’t knocking, regular fuel might still cause problems. One of the main issues that can come from skipping premium fuel is a loss in performance. Specifically, you might feel that the car runs slower if you fill it with regular fuel. You might also notice a drop in fuel economy since the engine probably isn’t running at its most efficient level, even though it isn’t knocking.

That brings us back to whether you must use premium gas. In many cases, you can get away with gassing up with regular fuel with no noticeable issues except for minor losses in performance and gas mileage. But it’s not worth taking the risk.

Bottom line: If your owner’s manual says that premium fuel is required, you should use it. But your car won’t blow up if you occasionally opt for regular.

Related Vehicle Fuel Articles:

Editor’s Note: This article has been updated for accuracy since it was originally published.

FAQ

Can you mix premium and regular gas?

Yes, you can mix regular gas with premium gas. However, combining two grades will dilute the overall octane level, which could cause engine performance loss on cars that require premium gasoline.

What number is premium gas?

Yellow stickers on gas pumps have numbers to indicate octane levels for gasoline. Premium gas has an octane level of 91 to 94. Regular unleaded is 87 and mid-grade is 89.

Which vehicles need high-octane gas?

The rule of thumb is to follow the manufacturer’s guidelines in the owner’s manual. If your car requires high-octane premium gas, that is the fuel to use in your vehicle. Using lower-grade fuel in automobiles that require premium gas may reduce performance and cause costly repairs later. In general, vehicles with high-performance engines require high-octane gas. Also, older cars with engines that begin to “knock” or “ping” might benefit from a tank of premium gasoline.

Doug Demuro
Doug DeMuro writes articles and makes videos, mainly about cars. Doug was born in Denver, Colorado, and received an economics degree from Emory University in Atlanta. After graduation, Doug spent three years working for Porsche Cars North America. Eventually, he quit his job to become a writer, largely because it meant that he no longer had to wear pants. Doug’s work has been featured in a... Read More about Doug Demuro

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6 COMMENTS

  1. I’m not sure anyone should follow my advice but I have a 2018 BMW X5 5.0 that ‘requires’ premium. I’ve never put premium in the car and have always used regular 87 octane. The car has 40,000 miles and I’ve never had an issue. Performance is excellent and I’m still faster than most cars on the road. I’ve never experienced any hesitation, lack in performance, etc.

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