Actually the T-34 was arguably the best EARLY war tank of the war because of it's sloped armor. Tigers ate Soviet tanks for breakfast on the steppe until the Soviets started building better Tank Desteroyers (the SU-152, I believe). At the battle of Kursk the T-34s (they weren't upgunned to the 85mm yet) had to close to point blank range to kill Tigers with side and rear hits.
Anyway, as has been stated before, the damage modeling seems to be screwy. However, I have noticed that if you hit certain spots on some vehicles, they die much faster. I was in a M8 shooting other M8s, and I noticed that if you hit the M8 on the extreme front on the left or right side (I don't remember which side), you can kill it a LOT faster (~2 hits). I assume this accounts for the driver being killed, but I don't know.