Study Finds Not All New Gas Burns Cleaner
New gasolines required by the Clean Air Act don’t hurt the performance or fuel-efficiency of cars, but sometimes they don’t burn any cleaner than older, cheaper blends, Consumer Reports said Monday.
The magazine conducted tests on new types of gasoline to compare acceleration, fuel economy and emissions against a regular-grade gas that met the 1990 industry average.
It found no meaningful difference in either acceleration or fuel economy among the various new fuels and the 1990 version.
But it did find that not all the new fuels burned cleaner than the 1990 gas.
The survey was conducted on four varieties of regular and premium grades: conventional, winter-oxygenated with ethanol, reformulated gasoline with ethanol and reformulated gasoline with MTBE (methyl tertiary butyl ether). Samples were purchased in Miami, Phoenix, Chicago and Houston
Samples of California’s Phase 2 reformulated gasoline, only available in that state, also were included.
The California Phase 2 fuel was the most effective in reducing emissions of carbon monoxide and hydrocarbons.
“The other new premiums are also doing their job--and without hurting acceleration and fuel economy,” the magazine said in the survey, appearing in its November issue.
It found, however, unexpectedly high emissions with the regular grades of three of the new fuels. Winter-oxygenated regular gas tested no better than the 1990 formula for emissions of carbon monoxide and hydrocarbons.
Regular-grade reformulated gasoline with ethanol and the new conventional gas were no better than the 1990 mix in emissions of hydrocarbons, although they did emit less carbon monoxide, it said.
As for performance between regular and premium blends, the magazine said it found no significant difference in acceleration or fuel economy.
“Stick with regular-grade gasoline unless your car owner’s manual advises otherwise, or unless your engine knocks,” it advised.
Calls for comment to several major gasoline manufacturers weren’t returned late Monday.
The Clean Air Act, first enacted in 1970, required auto makers to reduce pollution by improving the design of their cars.
In 1990, the act was amended to require gasoline in high-pollution regions to have an oxygen content of at least 2%, beginning in January 1995. Oxygen allows for cleaner burning, less-polluting gasoline.
The oxygen-content rule was expected to add 3 cents to 5 cents to a gallon of gasoline. Ethanol critics say because ethanol, or grain alcohol, is more expensive, it adds another penny a gallon, compared with methanol. MTBE is controversial because it may react with ozone to form formaldehyde. Both MTBE and formaldehyde caused cancer in animal tests, the magazine said, adding that MTBE was banned in Alaska.
Consumer Reports is published by Consumers Union, a nonprofit testing and information service for consumers.
The magazine also found that most gas stations offer three grades of gas: regular, about 87 octane; premium, about 92 or 93 octane; and a mid-grade, about 89 octane.
Octane rating is a measure of a fuel’s resistance to knocking. Continuous knocking, sounding like a ping in the engine, can damage the engine. But occasional light knocking driving uphill or under hard acceleration isn’t anything to worry about.
The owner’s manual tells which octane is best for a certain car. But using premium in a car that doesn’t have a problem with knocking won’t provide better acceleration or better fuel economy. What it will do, is cost more. High-octane gas can cost 20 cents to 30 cents more per gallon.
Some cars may eventually need higher octane fuel as engine deposits build up, but Consumer Reports recommends trying an engine tune-up before switching grades of gas.
