Assetto Corsa with Head Tracking: F1 GTR @ Spa 

Using Opentrack and FreePie on a Galaxy S4, I was able to get head tracking. Naturally, the first thing to do is take the F1 GTR for a spin at sunset Spa. Any old Android phone will do! Will likely tinker with the sensitivity but out of the box all that is needed is inversion of the pitch and roll axis.