huh?
Ost T2 plus BP1 plus BP2 plus P4 = 285 fuel
USF T3 plus T4 plus M4 = 285 fuel
Only way you're getting 255 fuel for the P4 is if you get an Osttruppen doctrine supply drop and maybe 235 if you skip T2. But these are very specific tactics with huge drawbacks so there's really nothing to complain about.
You should check your numbers.
Full tech Ostheer into Pz4 is only 275 fuel I don't know how you find 285 for a rush, USF 1 tier tech full upgrade is already 305 fuel.
The only way for USF to reach that 285 fuel you mention is to build only an ambulance with 1 full tier. Good luck fighting Pzgren without BARs.