Finally got one from Google, but this one was reviewed way back in 2005 pa. --> link

I guess this one is somewhat similar to MagnaFuel:

"MIRACLE MAGNETS

According to the people selling these devices, as gasoline flows past the magnet, the magnetic field will "break apart clusters of fuel molecules so gas burns more efficiently." Problem: Gasoline molecules aren't magnetic, not at all. But wait, there's more. If the fuel line is steel, as many are, the lines of magnetic flux will follow the fuel-line walls instead of passing through the fuel.

THE DYNO SAYS: As we suspected, neither device had any significant effect on performance or economy."