- Joined
- Jan 3, 2013
- Messages
- 7,540
- Car
- AUDI S8 V10, S210 E320 CDI (R.I.P.)
They are activated charcoal filters and as Gav said they are not cheap so most people don't replace them (or probably use them!). They are intended for when following HGVs (or taxis etc) to filer out the smoke etc. I had them on my W210 but they were only fitted to cars with auto climate control. Not sure of the set up on a W211 but I would have thought being the top spec they all have climate and therefor this filter too but obviously not.