Fuel saving gadgets

Feb 24, 2006

A Kettering professor has his students test the mettle of some products claiming to improve fuel economy by putting the pedal to the metal.

Dr. Greg Davis, professor of Mechanical Engineering at Kettering University, has spent a lot of time recently answering questions about devices and additives designed to improve fuel economy in cars.

Davis is skeptical of most devices and additives, saying that driving habits are the single largest contributor to fuel efficiency.

When yet another reporter contacted him to talk about acetone (yes, nail polish remover) as a fuel additive to improve gas mileage, Davis decided to put the product's claims to the ultimate test - let the students in his Advanced Automotive Power Systems class run real scientific protocols to test the performance of acetone in gasoline in a real car engine.

With a Buick 3800 V6 engine on the test stand in the Lubrizol Engine Test Cell Laboratory at Kettering, students ran the engine at 2000, 2250, 2500 and 3000 rpms, at 15 and 25 percent throttle with varying loads of stress. In layman's terms, they hit the gas, opened the throttle and programmed the engine as if it were driving on flat ground, up a steep grade or pulling varying loads.

Their initial results were almost opposite to those in articles they found on the Internet supporting the claims that acetone as a fuel additive improves fuel economy. "Research we found on the Internet showed a 35 percent increase in fuel economy," said Lee O'Donnell, of Vancouver, British Columbia. "Our findings essentially showed no improvement in gasoline economy," he said.

Their 15 percent throttle open test with acetone showed little to no difference from their baseline test with just straight gasoline. "Combustion efficiency is pretty high with gasoline," said Lee, "you really can't improve on what is already on the market."

"In most cases you can assume that the engine is burning 100 percent of the fuel," added Aaron Meyer, of Niles, Mich., "the claims of the acetone additive company say it helps the engine burn 100 percent of the fuel, and because engines are designed to burn between 98 and 100 percent anyway, the additive isn't really effective in altering fuel economy."

Even with their initial test results showing no impact on fuel efficiency using an acetone additive, Davis said they need more data to make it scientifically accurate. "Although we can say with confidence at this point that there is little to no effect," he said, "we'll repeat the testing to get more data to help determine if there is a gain or loss of even 1 percent."

"Driving habits heavily influence gas mileage and fuel economy," said Davis, "and speed has a big impact too, mainly because of increased wind resistance. The wind resistance at 60 mph is four times that at 30 mph, he said.

On the British web site "Tony's Guide to Fuel Savings," an unnamed engineer, who has worked at Bosch and Cosworth Technology, offers advice and comments on fuel saving gadgets. His commentary agrees with that of Davis and his students. It states measurements showing emissions reduction and improved fuel consumption ignore that performance increases are extremely dependant on driving style and that uncontrolled testing under variable conditions does not constitute proof.

Davis and his students agree, they are sticking with proven scientific methods to conduct their fuel economy tests.

Written by Dawn Hibbard