H H O
People have tried to sell me kits for $89.94 that run off a 40 amp fuse. These kits feed the Hydrogen /Oxygen mix (known as brown gas) through a 1/4" hose. The volume of the HHO gas flow is so tiny, it is insignificant in comparison to the amount of fuel / air mix going into the intake manifold. They may increase gas mileage at low engine speeds , but to see a significant difference, you would need a huge amount of the HHO gas, many times what the kit would be able to produce. A one liter engine will take in 1/2 liter of air/fuel mixture per revolution, hence if your engine is running at 2500 RPMs, you would need to produce upwards of 1250 liters per minute of the HHO gas per minute.
I was also told I could run my 1928 Chrysler off of the HHO produced from 2 of these kits and would never need to put gasoline in it. Ya, right 80 amps running a car at any speed. A lawnmower wouldn't run off of that.