We do not pull out the birth of the universe etc etc, the energy of the zero point has nothing to do with the present world and still ? the form of the idea, that cold fusion does not work at the moment (I have watched with interest the old ITER project from when they started to talk about it). We pull out topics that are not related.
Here we talk about the efficiency of a complex electrolytic cell - engine combusitone internal. I believe that the only advantages that may be from the contribution of hho to the engine are optimization of combustion, but let me doubt that thing can change in a motor 2L, the contribution of 1L/m hho.
The main issue ? the alternator avr? a dispersion of energy (in the form of mechanical - see the belt and the pulley - and form into electrical energy);
the electrical cables, they shall be separated;
the electrolytic cell is not the avr? performance unit.
At the end from my point of view already? to pay back what you spent (in terms of improving the efficiency of the engine) will be? hard.
Another matter if the purpose of this system ? for reasons of pollution (which would have to be checked).
PS: The chapter plants to natural gas - lpg on-ignition engines compression-let's talk about it in another discussion, they are completely different from cells and hydrogen, and they, too, have a lot of current relevance