I suspect that vehicle supplys either repairs all damage, or just leaves damage to the armor (and tank) from non-critical hits alone.
I mean I haven't noticed any strange paper armor after taking supplys, but I haven't seen any difinitve evidence either way to show if it fixes all damage, or leaves non-critical damage alone.
And to test it, we would have to test how our damage model works. By this I mean we will have to test and see if its an overall HP-based system, internal component-based system, or a combination of the two.
What I would suggest is that you and a friend go to the DA. Both of you up jeeps, and one of you fire at various locations on the other jeep. Fire at the same location 5 times, and see if there is a hard-set number of rounds that each location can take, or see if it varies at all.
Up an M3, and do the same. Fire at one point on the M3 at a time, and check to see if the number of rounds that each location can take before the part is damaged or the vehicle is destroyed varries.
Repeat with each vehicle, using the weakest gun possible (as this will give us the most precice damage thresholds).
This will show us if the damage model is HP or component based. If it uses an overall HP system, we should see a hard-set number of rounds that each location can take. If its component based, it should vary slightly, as point of impact changes.
And even if we get some ambiguous results, we can still see if there is any randomization at work in the GV model.