From what I've read (I've never had a lucid dream, although it has been proven in some of my NDs), mechanics either never work, or they always mess up.. Same with light switches and such.. Guess it is just not so natural (e.g. electricity running through wires to light up one object may be a little too much for your brain to process with all the other stuff going on).

From memory, my ND have included driving.. although the car was just moving, not sure how much control there was over the vechile, if any.