I have a 335d and after 2 months I had some exhaust smell coming in through the vents so I popped the hoode to have a look around the engine.
While looking around I noticed that the smell was very intense around the turbos so I has a closer look with a flashlight and I noticed a lot of oil was leaking out around the turbo.
I took it to the shop and they replaced the turbos.
Now I still smell exhaust from time to time and I hear a lot of ticking noises around the turbo and the exhaust.
I bought a carbon monoxide detector which goes off every few minutes...
not too happy with this car...