How the EPA Tests Fuel-saving Devices

How Fuel Saving Devices Say They Work

We take vitamins to stay healthy, Prozac to stay sane, diet pills to stay thin and aspirin to stop a headache. That's probably why putting a fuel additive in your gas tank to improve fuel economy seems to make sense to most of us.

That is, until you remember that people and cars are not, in fact, the same thing.

Most fuel additives claim to improve fuel economy by cleaning or removing impurities from an engine's internal components. That sounds pretty intuitive. An engine that's gunked up won't run as efficiently. Some gas companies even advertise that their fuel will clean your engine -- so why wouldn't an aftermarket fuel cleaner work?

Some fuel saving products claim to ionize the gas in your fuel lines for better mileage. Others say they'll use power from the car's battery to split water molecules into hydrogen and oxygen, which your engine will burn instead of gas.

Other fuel saving products claim they can help improve air intake to the engine, resulting in more power with each stroke. That also seems to make intuitive sense. After all, proven products like superchargers and turbochargers make more power by bringing more air, or cooler air, into the engine. Also, it's a common recommendation that keeping your air filter clean will result in better fuel economy because the engine won't have to work as hard to breathe. So why wouldn't a device that says it brings more air into the engine improve fuel economy?

That's what a lot of consumers wondered. So the Federal Trade Commission tasked the EPA with finding out.