From Bankrate.com:
Over the years, the U.S. Environmental Protection Agency has tested myriad gas-saving devices that burst onto the consumer scene.
Experts say they all have one thing in common. "They don't work," says John Millett, spokesman for the EPA. "Believe me, if it were that easy, cars would be built that way, especially the magnets and whirligig devices. It's smart to be skeptical about any claims like that."
The EPA to date has tested in the neighborhood of 100 gas-saving devices, and only six "indicated a very small improvement in fuel economy without an increase in exhaust emissions."
Popular Mechanics magazine's experts tested seven fuel-saving products for its September 2005 issue and found no significant change in miles-per-gallon ratings. Two actually increased fuel consumption by 20%, according to the writer, and a third one melted before they could complete the test.
But none of this evidence stops an eager entrepreneur from pitching his product to people tired of watching the gas pump numbers spin.
[For example,]"this gas-saving device is approved by the federal government." According to the FTC, no government agency endorses gas-saving products for cars.
