Might I suggest you sell your car and buy a HUGE projector!
I don't have a car... But I did cough up an IR head tracking program using OpenCV for using it with FlightGear, ultimately wanting to use some video goggles. It works fairly well, though it tends to lose track when you're jerky. That's without any optimisation done, however. As with FreeTrack & Co., you need to build yourself a very ridiculous hat with LEDs on it ;-). The program is really simple and head tracking would be REALLY great with Outerra - so if you're interested, I can post it here.
Alternatively, I actually thought of strapping a mobile LED projector to a helmet and building some sort of spherical screen instead of video goggles :-). Would look even more ridiculous - at some point you might be asking yourself if it's not a bit of a bore having your girlfriend laugh at you every time you play around with Outerra...
That is a great thing ! ... how is the handling done in your "sim-pit" ? Are you just lean to the sides/front/back on some pressure-sensors hanging ?
Yes, there are three struts attached to the control bar, one of which you can see disappearing to the upper left corner. This fixes the bar and there is a force sensor on each of them. The measured forces are then fed into JSBSim using the "external reactions" function; it allows you to introduce virtually arbitrary forces on your aircraft. This is great for simulating hanggliders, because our control moments behave differently as those from aerodynamic control surfaces (rudders, elevators etc.).