I have a lot of creaking from the back seats area of my E90 when I pull into a driveway for example or anything that places horizontal torsional stress on the chassis. Doesn't really bother me but it would drive me nuts if it was constant and I could hear it over my annoyingly loud exhaust.
My previous sedan never creaked or rattled in the three years I had it. I have no doubt that modding suspension and exhaust systems etc causes more rattles/creaks because of the additional vibrations through the car. Just not sure if its causing the creaking I'm experiencing.
Would love to hear from anyone with the same noise that fixed it tho.