I wouldn't bother with DAB mine just switches to FM every two minutes due to signal. It only works I find on an open motorway. Around town its hit and miss.
There is a problem with yours - there was an issue with cars with Tom Tom live traffic (where the live traffic GSM transmission interfered with the DAB reception).
MB issued software and new antenna amps to help (and then moved the aerials on newer cars !)
NTG4.5 DAB works well in both my W166 ML and my W176 A class (but note there is another bug happening around where i live - see a thread I am about to post)
R