If sitting in the co-drivers seat of an HEMTT and you roll (not turn) your head left or right whilst using Track-ir, the players view in first person perspective is that the whole HEMTT rotates. That is the major issue.
A lesser issue is that the view from the driver seat is different but also incorrect because when you roll your head left or right the dashboard and windshield and the world outside are tilting. This is the same in all road vehicles in the game. This does not happen in real life.
When controlling infantry in first person perspective rolling your head left or right has no effect on the your characters view and this should perhaps be the same in vehicles. {F20378}