Tanks are mannable.
I like the idea of being able to drive a tank like a tank, but I think our GVs are just a modification of the A/C model, and have inherited some odd behaviors.
As examples off the top of my head. Start a tank up, and the nose dives, and the tank bounces up and down. Now, I've never driven a tank, but I've driven all sorts of tractors and some small tracked vehicles, from Bobcats to Steiger Panthers, and none bounced or nosed down 10 degrees from the torque of the starter.
The Jeep is not capable of sliding, but it will roll end over or on its side for days. It will also not turn sharply.
Start a vehicle up, and push the stick forward. The vehicle will start to roll backwards. This is a great one when you're trying to get out of the way of bombs on a field. The tank is on flat ground and not in gear, but rolls. At the same time, the vehicle can not be put in gear while it's moving, which seems odd in that it shouldn't be moving since it's not in gear in the first place.
Anyway, while I appreciate the notion of fully realistic and historical modelling, why in coad's name would you waste that effort on GVs?