Vehicle wheels spinning in place / chassis jitter with identical snippet code (PhysX 3.3.3)

Sorry for the long title, but I wanted to sum up my problem in it.

Basically I copied the Vehicle4W snippet exactly into my code and the vehicle doesn’t move and just jitters.

This is my code: http://pastebin.com/G84uQ0D0
And my “simplified” version of the original snippet: http://pastebin.com/QnKAyt5h

The code is a bit long so I posted the PasteBin links above.

I also made 2 simulation recordings with PVD and uploaded them to my Google Drive along with a video recording and my full “project” source.

The code is absolutely the same, the only thing that could be different would be the stepping, but it’s still a 1/60 step (the relevant stepping code is in LogicGameState which gets called from the threading setup in Tutorial06_Multithreading.cpp)

Help and pointers are much appreciated.

My first guess would be that the wheel isn’t getting any friction or that the car has a collision volume touching the ground.