Gasoline saving products that are considered not only to be ineffective by the EPA, but also as illegal tampering by the Federal law, belong to the category of air bleed devices, internal engine modification and liquid injection. Thus, it would be better to perform a thorough research before you purchase one.

There are other gasoline saving products that do facilitate improvement of the fuel economy, although by a very less degree and neither do they increase the exhaust emissions. These gas mileage improvement devices do not seek to meddle with sensitive components or systems of the vehicles, rather they focus on improving the driving habits of the driver.