The Environmental Protection Agency did tests on over 100 fuel saving devices and found that most did not improve efficiency at all and the rest didn't improve it by that much.

Fuel efficiency products come under a few different categories. Some of these categories are: vapour bleed devices, fuel line devices, mixture enhancers, ignition devices, engine modification devices, fuel and oil additives and driving habit modifiers.

The EPA could only test for whether these devices has any impact on fuel efficiency. The could not examine whether these gadgets would do any harm or impact the vehicles performance over a long time.

For example, if an "air bleed" device actually adds significant amounts of air to the air-and-fuel mixture, it may cause an engine to misfire, a condition which greatly increases the potential engine damage or mechanical failure. This is especially likely to happen on cars manufactured between 1974 and 1982, because their carburetors are pre-set for a maximum amount of air to be burned with the fuel. "Air-bleed" devices will not work at all on many cars manufactured after 1982, because these cars have "feedback" carburetors that automatically adjust the air-and-fuel mixture rendering the device useless.

There are too many factors that affect fuel consumption such as driver's habits, condition of the vehicle. Because of this it is hard to believe the claims many of these product manufacturers make.

In one testimonial, a consumer gave high praise to a fuel saving device. What they failed to mention was that the car had also had a service at the time the device was put in.

Some advertisers claim that the gas-saving device is approved by the Federal government. No government agency endorses gas-saving products for cars. The seller can only state that the item has been tested by the EPA. If the advertiser claims that the product has been tested by the EPA ask to see the results or contact the EPA directly.

You may have already bought one of these devices. If you are not happy then you are well within your right to ask for a refund. Any honest company will offer a money back guarantee. If they do not, you can file a complaint with the state consumer protection agency.

Regular maintenance and servicing is one of the best way to ensure that your vehicle is running at it's maximum fuel efficeincy. You can find out service intervals by looking in the vehicle manual.

Here are three tips that will help make your vehicle as fuel efficient as possible:

Getting a tune-up.

Make sure your tires are inflated to the correct pressures.

Removing any excess weight from the car's trunk.