Check this out.
http://www.topbuy.com.au/tbcart/pc/Fuel-Saver-for-gas-and-diesel-engin-p91450.htm
I beleive that this works on the removing the negative waves from the electrical system of the car.
Now it is well known that the negative waves affect the fuel economy by making the alternator unhappy.
This is a direct result of the inverse parralel wave of the Plasma induced coefficient of the reverse sine wave harmonic that the occupants of the car create.
All of this then affects the combustible coefficient of the octane cetane relationship of the transverse coefficent of the weight of your right foot.