You guys keep going back to the, "conservation of energy" thing and I'm not questioning that you can't simply generate the hydrogen and then use the hydrogen to operate an engine and generate even more hydrogen. It's a lossy system and ultimately you'll end up with even less efficiency.
But, that's only true if you are already getting the max energy from the fuel in the first place. If there's a way to extract more energy from the fuel as part of the function of enriching it with extra hydrogen (or hydrogen and oxygen) then you could get a net gain. That's all I'm saying.
You can argue that this view is invalid because I don't have the specific details of how to do it and, I don't suppose I could disagree. But, when someone does come along and do it, wont you be embar.......no, I don't suppose you will.