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Do you really need to buy premium gasoline?

Old folks may say that they don’t build cars like they used to, but the fact is, by any measure except perhaps styling, today’s cars are far better than anything that came before. A modern car delivers reliability, performance, and fuel economy that prior generations could only dream about. The only cars better than the ones we have today are the ones we’ll have next year, and the year after that.

Just in the last 10 years, fuel economy, torque, and horsepower have all risen dramatically. But those improvements don’t come without costs. Far more modern cars require or recommend premium gasoline than ever before. While you might expect that with a high-end sports car, many cars at the economy end of the spectrum now recommend premium.

If you don’t know what kind of fuel your car is supposed to use, it’s easy to check.  Just look inside the fuel filler door – the fuel requirements should be printed right there.

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So what’s the deal? To understand the issue clearly, we turned to the fuel experts in the U.S. Federal government. The U.S. Energy Information Administration is an independent, policy-neutral, statistical and analytical agency created within the Department of Energy. As such, they’ve got no axe to grind for the oil or auto industries; they just deliver the facts.

What’s so premium about premium?

When you pull up to any standard gas pump in America, you typically have a choice between regular, mid-grade, and premium fuel. Each is labeled by its octane rating – typically 87, 89, and 91, possibly up to 93 in some states. Predictably, the higher the fuel grade, the higher the price. There’s usually a spread of about 20 cents per gallon between regular and premium.

Octane ratings indicate the performance capability of the fuel. Higher octane ratings mean that the fuel can be compressed to a higher ratio without detonating. That’s why high-compression engines need the more expensive premium fuel.

But apart from that rating and the price, is premium fuel really any different from regular? Mason Hamilton, Petroleum Markets Analyst at the EIA, offers some insight into how gasoline is made.

“Think of gasoline as a cocktail,” Hamilton told Digital Trends. “You need to blend certain ingredients to get a good-tasting cocktail. Regular gasoline is like a simple drink, but premium takes a more complicated blend to get the higher octane in there. They put in alkylates and reformates, which are like putting very expensive Italian or French Vermouth in the cocktail. So it takes a bit more pocket change to buy a gallon of that gasoline.”

Why does my car need premium?

Since 2013, the percentage of premium gasoline in total retail gasoline sales has been on the rise. In August and September of 2015, premium accounted for 11.3 percent of all gasoline sold to the public. That’s the highest share in more than a decade.

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There are a number of reasons for premium’s increasing market share, starting with low fuel prices. When gas was more expensive, many people chose regular whenever possible. But the bigger reason for the long-term rise in premium sales has to do with the cars we’re buying.

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The U.S. government specifies Corporate Average Fuel Economy (CAFE) regulations, requiring automakers to hit a range of 40.3–41.0 MPG starting in 2017. By 2022, average fuel economy standards will rise to 48.7–49.7 MPG. Let that sink in and you’ll see why automakers are spending billions to develop electric cars.

But to meet today’s CAFE standards, automakers are implementing a wide range of technical solutions to improve fuel economy. Obviously, hybrids, electrics, and diesel are part of the solution, but most of us will see a shift to smaller engines and smaller, lighter, more efficient cars in general. But at the same time, we love our horsepower and acceleration. What’s an automaker to do?

If the automaker says your car will run on regular, there’s no point at all in buying premium.

You’ve doubtless noticed a general trend of engine downsizing coupled with turbocharging. Every major automaker now wants to sell you a 1.4- or 1.6-liter turbocharged engine. The good news is that those engines deliver the necessary fuel economy while meeting or exceeding the horsepower and torque of older, larger engines.

“Corporate Average Fuel Economy is requiring automakers to get more performance out of their automobiles,” says David Stone, Automotive Engineer at EIA. “There’s a lot that’s changing to drive us towards higher compression engines. For example, direct injection also allows us to run higher compression, and higher octane helps allow that to happen.”

What happens if I use regular?

Many drivers whose cars specify premium fuel have filled up with regular at one time or another. Are you rolling the dice with your engine if you cheap out on your fuel?

The first thing is to understand the difference between a car that requires premium fuel and one that recommends premium.

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“In the past, a car may have required premium, but now many just recommend it,” Stone tells Digital Trends. “With some older cars, if it called for premium gas and you put in regular, it could damage the engine. Most cars today are smart enough that it won’t hurt them [to run on regular] but it will degrade performance and you might get reduced fuel economy.”

More important, if the automaker says your car will run on regular, there’s no point at all in buying premium. It doesn’t matter what altitude you’re at, how hot it is, or how fast you plan to drive.

“Feeding better gas than what is recommended for your car is a placebo effect,” Stone says.

Can I be sure I’m really getting premium?

So, assuming you know what fuel grade your car should be using, how can you be sure that you’re getting what you’re paying for?  What is there to prevent a gas station from pumping regular into your tank and charging you for premium?

By 2022, economy standards will rise to 48.7–49.7 MPG. You see why automakers are spending billions to develop electric cars.

“You have to remember that you’re not the first person to have paid for that gallon of gasoline,” Hamilton advises. “When that gallon of gasoline was created at the refinery, the refinery made it to a specific specification. That refinery sold it as premium, and handed over the papers to the buyer to prove that the gasoline meets the spec. The distribution terminal will do another check. Then there’s another series of checks when it gets loaded into the truck. By the time it ends up at a retail gas station, it’s been checked and checked and checked. There’s very little incentive for a gas station to sell counterfeit gas.”

On top of the quality assurances provided by the gasoline vendor, virtually every State government has an office of weights and measures that certifies that you’re getting a full gallon of gas, and that the gas meets the state’s standards for composition and quality.  There’s usually a sticker somewhere on the pump that tells you when it was last inspected and certified.

Buying top tier fuel

Many automakers, including Honda, Toyota, Volkswagen, Mercedes-Benz, Audi, BMW, Fiat-Chrysler, and all GM brands recommend “Top Tier” fuel. This fuel is certified to exceed EPA specifications, particularly in the amount of detergent added to help keep engine parts from accumulating deposits of impurities. It is always safe to put Top Tier fuel in any car, regardless of whether the manufacturer recommends it.

Over thirty U.S. brands, including Arco, Beacon, BP, Cenex, Chevron, Conoco, Costco, Esso, Exxon, Kwik-Trip, Mobil, Phillips 66, Shell, Sunoco, Texaco, Union 76, Valero, and others all adhere to the Top Tier standard. If you’re not sure about a brand, just ask at the station.

The bottom line on fuel

When it comes to the fuel in your car, there’s not really a lot of difference between major brands. Gasoline is one of the most regulated products available for sale to the public, and as long as you stick to the requirements and recommendations that the automaker provides for your car, you’ll be fine.

Related: The 54.4-mpg milestone: How will new 2025 CAFE standards affect you?

Even if you have to buy cheaper gas to make it to payday, most modern cars can handle it. And if the idea of paying more for premium bothers you, that’s a factor you can easily check before you buy any car. Just pop open the fuel door.