It's kind of a low grumbling and its loud when driving and coming to a stop. Not when idling. The dealer just agreed to replace 3 out of 4 tires at no cost since I just got the car Friday. They think this is the source of the noise. I was also told by my salesman that I was getting the top line stereo which it is not. It's the hi fi one, not the Logic 7. So for that, they are giving me an ipod interface upgrade from the MP3 player. They said they'd do all that or I could pick a different car. I think I'll stay with this one and hope that soon I'll have the awesome driving experience everyone seems to have with their BMW!