Water for gas

[merkzu]

But the extra electricity comes from your gasoline, it isn't free - so I dont get where any gas savings would come from

Think of it this way, if you used a large number of HHO units - enough for the engine to run on completely HHO. And then you attached a device to collect all the water from the exhaust, and feed that water back to the HHO unit.

You would be able to run the engine forever on the same water, splitting it up into HHO and then recombining it into water forever.

It sounds an awful lot like a perpetual motion machine