FWIW, I use the TrackIR with racing sims. The problem with most racing sims is that they do not support it. Grand Prix Legends (GPL) does (with a third party add-on), as does rFactor. I recommend both ...
I want to smash the Trackir tracking system for being a superfluous, dork-oriented gaming appendage, and it totally is, but in the sort of way of way that makes me want to play flight simulators again ...