Over the last 20 years, new car fuel economy, horsepower, and torque have all risen dramatically. Driven by these significant increases, many modern cars including Mercedes-Benz now require or recommend premium gasoline, while many older Mercedes models can run just fine on regular. 

There's lots of interesting information below, but we'll cut right to the bottom line: If Mercedes-Benz says your car will run on regular, there’s no point at all in paying extra for premium. It doesn’t matter what altitude you’re at, how hot it is outside, or how fast you plan to drive.

If you don’t know what kind of fuel your Mercedes-Benz is supposed to burn, it’s easy to check.  Just look inside the fuel filler door; the fuel requirements should be printed right there. If they're not, then check your car's original owner's manual. 

Expert advice

To clearly understand this issue, we turned to the fuel experts in the U.S. Federal government. The U.S. Energy Information Administration is a formally independent, statistical and analytical agency created within the Department of Energy. As such, they’ve got no axe to grind for either the oil or automobile industries; they just deliver plain facts.

When you pull up to any gas station 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, or up to 93 in some states. Octane ratings indicate the performance capability of the fuel. Higher octane ratings mean that the fuel can be compressed to a higher ratio without pre-detonating. That’s why high-compression engines need more expensive premium fuel. Predictably, the higher the fuel grade, the higher the price.

“Feeding better gas than what is recommended for your car is a placebo effect,” says David Stone, Automotive Engineer at EIA.

Lower-grade fuel

Many drivers whose cars specify premium fuel have filled up with regular at one time or another. Are they risking engine damage? The first thing is to understand the difference between a car that requires premium fuel and a car that recommends premium.

“In the past, a car may have required premium, but now many just recommend it,” Stone tells The Star. “With some older cars, if the owner's manual calls 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.”

Top Tier fuel

Many automakers including Mercedes-Benz 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. petroleum 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 any given brand, just ask at the station.

So, it turns out that there really is not that  much difference between the many different Top Tier fuel brands. Gasoline is one of the most regulated products available for sale to the American public, and as long as you stick to the requirements and recommendations that Mercedes-Benz provides for your car, you’ll be fine. Fill’er up.