You handle criticism so well Mech
Anyway, yah it looks like there is a continual friction drain in a hydraulic system. Especially if you have to rely on regen/bsfc to make it look good. Sorry you missed that. And throwing hydrogen in the mix is kinda cheating. You are setting the stage for all number of errant claims by not isolating the variables. And my other critiques have gone unaddresed. Here is another problem, that I don't expect you to be able to take objectively.
Premise(not agreeing, just saying): folks should be driving at constant speeds, this makes that possible to do efficiently.
Problem: If you are operating at a constant speed, you can achieve peak bsfc with a correctly sized/geared engine. If you make a series hybrid out of it then you lose efficiency at constant cruise, perhaps a lot of efficiency. There is no evidence that your hydraulic transmission is anywhere near 94% efficient at turning engine and flywheel power into wheel power under extended constant load conditions.