The process of buying a car often involves a lot of research, and sometimes your research will reveal that the car you want requires premium fuel. This can be a big disappointment, since premium gas often costs 30 to 50 cents more than regular gas on average. Can you buy the car anyway and just skip the premium gas? We have the answer.

Why Premium?

A discussion of whether or not you need to use premium fuel has to begin with an explanation of exactly how premium fuel differs from regular gas. Many drivers think premium is more refined than regular or that it's cleaner, but that's not the truth. In fact, it's simply less combustible than regular gas. What exactly does that mean?

Although we'll spare you the mechanical details, the important 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 have a tank full of regular. Too much engine knocking could cause damage, and it certainly means that your engine isn't running very well, which isn't something you want to deal with after buying a car.

Why Only Some Cars?

Considering that premium fuel seems to prevent engine knocking, why don't all cars take premium? The answer lies in the engine's construction. A typical car, for example, doesn't need a high-performance engine, meaning its engine uses a simple design with a low compression ratio that runs just fine on regular gas. Most high-performance or luxury cars, however, have more power and a higher compression ratio, which means that their engines are more prone to pre-ignition when using the wrong type of fuel.

Do You Have to Use It?

So you'll want to use premium fuel in a luxury car, right? Not necessarily. Most luxury cars have 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.

If your engine isn't knocking, regular fuel might still cause some problems. One of the main issues that can come from skipping premium fuel is a loss in performance. Specifically, you might be able to feel that the car is a little slower if you put in regular fuel. You also might notice a drop in fuel economy, since the engine probably isn't running at its most efficient level, even though it isn't knocking.

This brings us back to the question of whether you have to use premium gas. In many cases, the answer is probably no -- you'll likely be able to use regular fuel with no noticeable issues except for minor losses in performance and gas mileage.

If your owner's manual says that premium fuel is required, then you should do it, but your car won't blow up if you occasionally opt for regular. If your owner's manual says that premium fuel is recommended, then you can use regular gas all the time with no worries.

author photo

Doug DeMuro has a wide range of automotive industry experience, from work at a Ferrari dealership to a manager for Porsche North America. A lifelong car enthusiast, Doug's eclectic vehicle purchases include a Porsche 911 Turbo, an E63 AMG wagon, an old Range Rover and a Mercedes Benz G-wagen.

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