Is All Gas Created Equal?

By Dave Carpenter, AP Personal Finance Writer

CHICAGO (AP) — Hopeful signs about the economy and gasoline prices comfortably below $3 may tempt you to spring for premium when you pull up to the pumps these days.

Don't give in. Stay "regular."

Premium may sound like a way to pamper your vehicle and make it perform better or longer. But it's more often just a way to spend an extra few bucks a tankful when you don't have to.

"If your car can run on regular, just run it on regular," said David Champion, director of automobile testing for Consumer Reports. "By putting premium into a car that runs on regular, normally you will not improve its performance or fuel economy."

Here are some questions and answers about premium fuel.

Q: What exactly is premium gasoline?

A: A fuel with a high octane rating, which means it's less likely to cause your engine to knock or ping. Premium gas has an octane rating or anti-knock index of 91 or 92 in most of the U.S., compared with 88 to 90 for midgrade and 87 for regular.

Some higher-octane gas also may have cleansing additives or detergents, which ensure that the fuel lines don't get gunked up with deposits. But regular gas has gotten better over the years and generally keeps fuel injectors and intake valves clean. Most cars also have anti-knocking sensors which adjust to the type of gasoline.

Q: How much more does premium cost than regular?

A: Roughly a quarter extra per gallon — more in some places — or an additional $7 or so to fill up an SUV with a 30-gallon tank. The average nationwide price for a gallon of premium gas as of Monday was $2.88, according to the Energy Information Administration. That compared with $2.76 for midgrade and $2.64 for regular.

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