Notice kind of a buzzing sound at certain RPMs from around the instrument display when I had the radio/air off. The sound was very short oscillations, not like a rattle. After some investigation I decided it was the springs for the steering adjustment system. Put some of those rubber glove type thingies over them and no more vibration. Mechanic said a couple of other Golf TDI owners complained but didn't know what it was and that it isn't an issue with the gas models. Less vibration I guess.