Well I figured out the issue with this script for the Tiger, its mostly related to the Torque values being extremely rigid, if you go too far out of what they are (~400) such as 1850N.m which is what the Tiger 2 had then it basically stalls the script in a loop.
I'm in the process of finding where this hold up is happening, being the very amateur that I am, this could take some time. It will be some basic value, will figure it out.
Edit: Seems the max torque you can have before things go downhill (tank doesn't move) is around 700. Will continue looking into this tomorrow.
Edit2: So the problem turns out to be a double edged blade, yes the script does react odd when dealing with high torque engines, but the main contribution to the Tiger 2 movement problem is you (M7) have specified weights (large) inside the model itself, thus compounding the issue. You should only use a 0-1 value to help with balance then when you put the mass in with the scripts it distributes this correctly.
Atm the Tiger 2 tank appears to have ~10k-20k weight added to it via the model alone
(you specified 20k in the script, this is added to the model weighting/or multiplied, whichever). Outtera appears to factor this into its own mass calculation (as to determine weight distribution and balance, or the tank would flip over etc) thus you have a compounding effect. I will now just move onto making my own tank (Sherman firefly or something), my skills in this area have been dormant for 10years, this will be interesting to say the least, LOL
PS. I'm 10years rusty to all this tank building and script stuff, please be gentle with me if I turn out to be completely wrong