When I complained about this Hitech said it was part of the auto heading feature of GVs- in other words it's an underdamped oscillator. You bring the tanks heading say 45 degrees to the left and try to straighten out and the tank turns back by itself to something like 20 degs to the left of your initial heading. I find it extremely annoying: you see a tree ahead you turn to miss it but the tank just turns back towards hitting it and you have to turn again. Or you anticipate this effect and way oversteer your tank knowing it will turn back. That, however, slows you down since turning engages brakes on one track and having to way over turn also means more slow down than necessary. However, only about 20 to 25% of AHers are tankers so this problem is unimportant.