This is a tricky one. I suspect what is actually happening is that the tank is both not canMove and not canFire. I doubt the crew would disembark if it could still fire.
The problem is that usually the two conditions occur together: the cases when the tank can't move but can fight are relatively unusual.
Since you want a particular effect I would recommend scripting the whole thing. Add an eventhandler "hit" to the tank, and, based on the dammage received, set fuel, ammo and general dammage states accordingly. I would also recommend experiments to discover the levels of dammage that will create the various conditions in which you are interested.
In other words, forget canMove: what you actually want is a tank dammaged 0.7 (or whatever) with setFuel 0 and plenty of ammo. That is the endstate you actually want, how you get from the [first, second or third, etc.] hit to that state is up to you, the mission designer.