There are different kinds of rattles associated with the 3-series. Mostly from the HK sound system. I myself do not have the rattles from the HK, I have a 330i without folding seats, perhaps the folding seats are causing the rattles? I may be wrong. Another rattle lie in the pillars and trunk. I also do not have these rattles. I thought I had a rattle from the front passenger side pillar, but it was only the seat belt buckle that was not resting correctle between the seat at pillar. I've been hanging around here lately and reading about problems with rattles. How bad are they and are they isolated to the coupe or sedan? Thanks.