Well if you dont think a unit with 560 hp, 50 range, 140 penetration at max range, twp and a machine gun is worth 75 fuel, I dunno what to tell you. Maybe it could be 70 fuel. Also StuG isnt just to kill t70.
It was already said, for which puprose you will be build stug sa 1-st unit? That's why i point on t-70.
You build T3, t-70 already running over battlefield - which unit you will build 1-st? Stug? Ostwind? Or save fuel to P4? IF you choose P4 - you have hardcounter to any LV and could also fight against any future medium and have very potent AI platform. Choose Ostwind - also good, very strong AI + counter LV, only need don't die against 1-st medium, but when 1-st ally medium will arrive, you almost have fuel on P4 or stug.
Only one real option to build stug - ostwind+stug. Not other. Or heavy ally medium spam. It's just question why soviet M5 so rare? Because it will build when you know, that your enemy choose doc with AT Stuka. It's not rare, it's just build only when you neeed it. Not sooner, not later.
If you think, that "new" cheap stug will be good, ok. I don't mind about it (i just point that, stats IMO too decreased). But you just brokening unit that already working, IMHO.
90 fuel is quite a bit for a dedicated anti tank unit with only 50 range. That said, its damage output is too high to be less than 90 fuel so by nerfing that you open up the possibility to make it a more affordable emergency unit like the m10.
You saw digits, stug could fight 1vs1 against any ally medium and always survive. Only 1 gren with faust to prevent flanking. I just can't understand why so many OST players thinking, that cheap stug will bring it "honor like in old days". Problem as was said in "meta". Allies don't build mediums in huge amounts.