My girlfriend has an 01 7 Series, and when it is running, the smell in the car is very strong of exhaust, almost to the point you can't breath. Turning on vents and rolling the windows only makes it worse. Also sometimes the car will stall, and while it's running it sounds as though it is struggling.
My thoughts were a clogged catalytic converter, because when it turns off the car turns back on just fine. Any thoughts?