Not unless i have to. I use voice, or my space navigator, which is rested right where my arm rests. To have any meaningful gesture support in a moving car you would need to have 2 hands creating the gestures. Mercedes actually had a car with gesture support at CES this year, and the first thing that was asked by testers was how is it feasible to use it while driving. The answer at that time was it wasnt, and that gestures would only work when the vehicle was stopped.
i't a nice cool factor, but to have gestures enabled only while not moving becomes unnatural. the best way to perform any function is to do it the same way all the time-- jumping between different control methods based on the vehicles status would mess with me..