They just fix the GV too quickly. When vechile supplies are dropped, I think this should happen:
Time 0: Ammo is restored
30 seconds after drop: Main gun restored
2 mintues after drop: Engine/Oil restored
It still doesn't take 2 mins. to change an engine, but it's something. As it is now, in Pazner vs. Pazner combat, if one panzer has supplies next to him....it's the same thing as having 10 lives.