Should gasoline be graded by its cleanliness?
Should you care how much detergent is in the gasoline you buy? How can you even tell?
Leading automakers BMW, General Motors, Honda, Toyota and Volkswagen think you should care, and they want to help you find stations that sell the cleanest gas. They want some fuels certified as best for fuel economy and emissions. Not everybody's on board, though.
The automakers formed a consortium, Top Tier Gasoline, that certifies retailers as meeting their standard for detergent. Detergents prevent deposits of leftover material from building up in engines and exhaust systems. The deposits, like the crust of minerals left when hard water evaporates, can reduce fuel economy and performance.
Top Tier also certifies there are no additives that reduce catalytic converter effectiveness. Top Tier stations account for just more than 50 percent of U.S. gasoline sales.
"We strongly recommend Top Tier detergent gasoline to keep your engine clean," GM fuel specialist Bill Studzinski said. "Fuel economy, emissions and acceleration all suffer when there are deposits in an engine."
Just like a campfire leaves a pile of ash, burning gasoline leaves residue in an engine, said Matthew Mio, associate professor of chemistry and biochemistry at the University of Detroit Mercy. The residue is like the plaque that can clog your arteries. "Leaving untreated buildup reduces the efficiency of an engine over time. Detergents take the plaque away."
The Environmental Protection Agency has required detergent in gasoline since 1995. It set the current standard, called Tier 2, in 2000. Top Tier argues that the standard is dated and insufficient for today's engines and emission systems and also for the more fuel-efficient models on the way.
"The ability of a vehicle to maintain stringent Tier 2 emission standards has been hampered, leading to engine deposits which can have a big impact on ... emissions and driver satisfaction," according to Top Tier Gas' website.
There's no independent data comparing the price of fuel at Top Tier retailers to those that don't meet the standard. GM says it hasn't found any consistent difference, and a quick survey of stations in my neighborhood supported that.
All gasoline has some detergent. Top Tier certification is the only way to know if what you're pumping meets the legal minimum or a higher standard.
The automakers who don't participate in Top Tier fuel are satisfied with the current standard.
Top Tier Gasoline measures the detergent in fuel at a lab. It also requires all grades of gasoline a retailer sells – regular, mid-grade and premium, for instance – meet the standard. That means certified gas stations can't put extra detergent only in premium in an attempt to force drivers to buy the most expensive fuel, as some others do.
Any gasoline retail group can ask Top Tier to evaluate its fuels. Many leading retailers have Top Tier certification, but many don't. They don't necessarily have less detergent, but they haven't been independently certified.
At least one company, 76 gas stations, now brags that all its gasolines exceed Top Tier's requirement.
ABOUT THE WRITER
Mark Phelan is the Detroit Free Press auto critic. He can be reached at firstname.lastname@example.org.
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