I literally proved you wrong 2 posts ago, your the one making outrageous claims. Some evidence would be nice.
It get's no acceleration bonus from vet, it gets the same speed bonus and rotation bonus as the SU-85 does and it starts less of those 2. The SU-85 will outclass the vet 0 JPIV in mobility at vet 0, and the vet 5 JPIV at Vet 3 in mobility.
The SU-85 has greater pen and reload than the JPIV while also having greater mobility and cone of fire. The JPIV has greater armor and better combat veterancy.
I'm starting to think you use the Jp4 like Jesulin Kappa. Doesn't utilize range, rushes it in as close as possible to the point where cons flank and at nade its ass. I would take a JP4 over an su-85 any day and I'd rather have more armor than reload. Starting at vet 1 that thing is even more potent than an su-85 (camo in the middle of a road or use it to save yourself from an at nade.)