270 (370 full) manpower is quite high for just getting healing (leig and flak ht dont offer much later in the game). That could be a mg, a raketen or most of an obers squad. So i dont think the fuel is the problem. Going all 3 tech structures is very manpower draining though.
And that for a faction who has mediocre mainline (Cons get 6,26 HP per manpower at vet3, Volks get 4,1 HP per manpower at vet 5; from that point Cons are 50% more efficient than Volks), expensive elite (cost compared to timing window),and just a few mediocre ways to deal with infantry later on. Imo the faction has major manpower problems later on in the game (atleast compared to SOV/Ost; Usf bleed the same but atleast their inf isnt shit)
270 mp is certainly a lot, especially if you back tech in the later stages of the game when there's less time left to recoup that expenditure. but as said before, i'd rather make healing for the other factions more expensive than to further water down the distinction between okw's two tech paths. imho the mp reduction soviets got for their in-base healing wasn't really needed in the first place, but anyway...
the mediocre scaling of volks, as you put it out in your example, is probably the most universally agreed upon flaw the faction suffers from at the moment. i'm not sure if a vet reshuffle as proposed earlier in this thread will be able to solve this, but a small bonus to RA at vet5 could certainly attenuate the late-game bleed a good bit.