What About the Generated Oxygen?
No one is saying anything about the oxygen that is also a product of water electrolysis. If the generated PURE oxygen is also stored, burning it with the generated pure hydrogen will provide much more power than burning it with diluted atmospheric oxygen (the atmosphere contains only 20% oxygen by volume). Burning pure hydrogen/oxygen will produce more heat, but it will have higher volumetric efficiency (more mpg) than using the diluted atmospheric oxygen. The added heat is a challenge, but our scientists will find a work-around for it (maybe use advanced ceramic combustion components).