I have plugged in g29 with g13, Xbox 360 controller and of course mouse.
Many people have problems in options to set them up, me also.
But while playing and using g29 for driving I use xbox 360 controller to look around and also my mouse. It deppends which hand I have busy so on left I have controller mounted to my stand pro and on right I have mouse.
So when I use mouse or controller to look around then I noticed that wheels are autocentering if I dont move my wheel while driving. With FF enabled it is hard to notice because wheel gives then imput and autocentering is not noticeable but on proving grounds I did test and drove in circle then use mouse to look around and wheels just straighten up. Same when I use right analogue stick on controller.

There is also interference between my wheel and a mouse, worked flawlessly on old ST game.