A commercial says: "Are gas prices hitting you hard? Introducing Fuel Doctor's revolutionary FD-47. Sources of electrical interference often prevent your vehicle's electronic control unit from sending out steady currents that optimize your engine's speed, timing control, and fuel injection."
The Fuel Doctor commercial goes on to say the FD-47 fuel-efficiency booster creates a more stable current, resulting in increased power and improved fuel economy. Consumer Reports wanted to see just how well the $50 Fuel Doctor FD-47 works.
"It claims to have the best effect on vehicles older than two years and also claims to have some effect on vehicles that are newer," says David Champion from Consumer Reports.
The commercial goes on to say, "Certified lab and field tests show increased mpg of up to 25 percent."
Consumer Reports tested the Fuel Doctor device in 10 different vehicles. Six of the cars were equipped with a highly-accurate fuel economy meter. Testers then measured fuel efficiency for both city and highway driving. The other vehicles were put through acceleration tests to see if the Fuel Doctor device increases power as claimed. Then the tests were repeated without the Fuel Doctor. So in the end?
"We found it made no significant difference at all. The only thing we saw, the light was on," said Champion.
Consumer Reports says what will improve your mileage avoiding fast accelerations and braking hard, watching your speed, doing regular maintenance on your car, and keeping your tires properly inflated.
Consumer Reports says for other gas-saving moves include not carrying things on top of your car -- that includes a roof rack -- and don't drive on worn tires.
Consumer Reports is published by Consumers Union. Both Consumer Reports and Consumers Union are not-for-profit organizations that accept no advertising. Neither has any commercial relationship with any advertiser or sponsor on this site.
(All Consumer Reports Material Copyright 2010. Consumers Union of U.S. Inc. ALL RIGHTS RESERVED.)