ROBERT SIEGEL, HOST:
For American drivers who choose premium at the gas station, AAA has a message. Unless your owner's manual calls for premium, you are wasting your money. The association says that more than 16 million Americans buy premium even though their cars don't need it. And AAA has a new study that's found that premium does not improve performance or gas mileage in those cars.
Greg Brannon is the director of automotive engineering for AAA. Welcome to the program, Mr. Brannon.
GREG BRANNON: Thank you, Robert.
SIEGEL: And first tell us what the difference is between high-octane premium gasoline and regular gasoline.
BRANNON: Well, the difference is really related to its ability to prevent detonation or that knocking sound that you hear in the engine from time to time. Those of us that are old enough to remember cars that didn't have the advanced technology that they do today will remember a time when that was much more prevalent. But really, the higher the octane, the better the gasoline is at resisting that detonation or pre-ignition.
SIEGEL: Well, tell us about the test you did to see what the effect is of premium gas.
BRANNON: We used something called a chassis dynamometer, which are dyno for short, which is more or less a treadmill for a vehicle. And through some very specific tests following EPA guidelines as well as a wide-open throttle horsepower test, we were able to very scientifically quantify the difference - or in this case the lack of difference - in both performance, emissions and fuel economy as a result of placing premium in a vehicle that is only calling for regular fuel.
SIEGEL: Why do you think so many people - more than 16 million people - spend extra money to buy premium if in fact there's no benefit, whatever to using it with a car that's not designed for premium gasoline.
BRANNON: It's certainly an interesting question. And as the report notes, over $2 billion have been wasted annually on that practice. I think it comes down to simply the naming - premium. You put premium on the pump, and the consumers likely believe that it is a premium product over the others on - that they have available to them and therefore are making that selection.
It may also have something to do with carry-over from a good time ago when cars weren't as advanced as they are today, and premium fuel may have helped with that spark, knock or detonation for those of us that are old enough to remember cars that did that regularly.
SIEGEL: You would buy no-knock gasoline in that case, as they would be - it would be advertised as such.
BRANNON: Exactly, exactly.
SIEGEL: Well, Mr. Brannan, if over 16 million Americans have been overpaying at the pump, buying premium for cars that - for which there's no benefit in using premium gasoline, have they been doing any damage to their cars by using premium?
BRANNON: They have not. The only damage is to their wallet.
SIEGEL: Well, on that note, thank you very much, and happy cheaper motoring.
BRANNON: (Laughter) Thank you.
SIEGEL: Greg Brannon, who's director of automotive engineering for AAA.
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