You need to launch in VR mode, should just work then. As far as I can remember at least. edit: you need to launch AMS2 in VR mode just to be clear.
not using head tracking at the moment but in an hour or so I can have a look and see if I'm forgetting anything. did you try switching protocols? free track vs trackir.
so yeah, once your in the car you have to switch to the helmet camera. You can set the helmet itself to invisible aswell. In VR at least having it visible tanks fps.