While I'm not certain of the science Uli Kruger is using in Lincvolt, the "water gas" you'll hear frequent references to in the garage is a form of hydrogen, or HHO, extracted from water, on-board the car, via a form of electrolysis. Hydrogen is bubbled from water using electricity in water fuel cells. Then, the hydrogen is drawn off and injected into the rotary engine as a catalyst to improve combustion. The byproduct in emissions (out the tailpipe) from the hydrogen burn is water. The hydrogen can also displace up to 50% of the primary fuel, increasing efficiency of the engine driving the generator, and effective MPG. This system is controlled by a blue box in the engine compartment labeled S.L.O.G.