I play a FPS called ARMA2 and when the player is in the commanders position, giving the orders in the tank (Move to position X---Y---, Open Fire, Target enemy Jeep 3 o'clock 350yards etc.) It has AI's doing the other things to maintain immersion and realism.
AIDriver drives and obeys orders (FORWARD,FAST,HALT,LEFT,RIGHT,REVERSE.)
The AIGunner, shoots things once given permission and reports enemies he see (ENEMY SHILKA 1 O'CLOCK 500 YARDS, ENEMY RIFLEMAN IS HISTORY, etc.)
I enjoy this type of tanking simulation it's pretty immersive, you as commander have don't have direct input over the tank but have to scan for targets aswell as giving orders for general movements and tactics, relying on your AI to 'do the business' like you would rely on a tank crew in RL.
Thought this might be helpful to look at