AAA says better gas is ... better
Why buy fancy-pants gas for a car when it's 10 cents a gallon less at Cheapy's gas station?
AAA is challenging that credo with a report that finds better gas is - better.
The U.S. Environmental Protection Agency requires fuel distributors to add a certain amount of detergent to gasoline that helps reduce carbon deposits. Some automakers have upped the ante by creating a "Top Tier" program that sets higher levels for additives in gas, which numerous fuel retailers have joined.
The AAA tested various types of gasolines and found non-Top Tier fuel left 19 times more deposits than brands in the program.
By using Top Tier fuel, "drivers can minimize engine deposits, increase vehicle performance and improve fuel economy," AAA managing director of automotive engineering and repair John Nielsen said in a statement.
Top Tier refers to different brands of gas and is not to be confused with various grades such as unleaded, midgrade and premium, AAA spokeswoman Beth Mosher said.
Top Tier gas brands include 76, Amoco, BP, Chevron, CITGO, Costco, Esso, Exxon, Kwik Trip, Mobil, Phillips 66 and Shell.
But not all Americans are buying the hype about premium gas.
AAA researchers found that 73 percent of drivers purchase gas based on the price and 75 percent because of location. Only 12 percent of motorists purposefully go to gas stations that offer Top Tier fuel.
AAA contends that Top Tier gas is typically three cents more than bargain brands and worth the extra cost because it will improve vehicle performance by eliminating problems such as rough idling.
When engine valves accumulate carbon "gunk," cars suffer, said John Walton, a Wheaton resident and vice chair of Chicago Clean Cities, a U.S. Department of Energy-backed group. Ultimately that means cars "blow through fuel and you don't get full power from them."
"When you buy BP and Shell you're aware of what the additive package is. When you go to an off-brand, you don't know what you're getting," said Walton, a vice president at Black Dog, a fuel supplier.
Argonne National Laboratory fuel expert Thomas Wallner called AAA's findings about carbon deposits significant but noted the study did not specifically measure engine performance and fuel.
"There is certainly a connection between deposits and engine performance - the magnitude of the effects would depend on the engine (and what technologies it uses) as well as driving behavior among other factors," said Wallner, manager of fuels, engine and after-treatment research at Argonne's Transportation Research Center.
Not included in the Top Tier retailers were Marathon and its subsidiary Speedway. A spokeswoman for Marathon declined to comment on the study.