Every so often, emails go around explaining how someone's cousin installed some device in his car engine and is now getting noticeably better gas mileage. These might be a device that alters the fuel or air intake systems of the car, using water for gas, or in some cases magnets or exotic metals placed outside of the fuel line to chemically change fuel passing within.
Sometimes, the explanations given by the companies peddling these products seems to make sense and at, other times, they are clearly nothing but double-talk designed to confuse the facts. Some reliable third party organizations have voiced their opinions and they all agree. Based on EPA testing of more than 100 such fuel economy improving devices, the Better Business Bureau, the EPA, and the Federal Trade Commission all agree: don't waste your money. None of the aftermarket products tested by the EPA have resulted in substantially improved gas mileage.
