Obviously this applies to the newer cars, if you are in a market for the 1996 to 1999 E calss diesels watch for this trap. On my E320 one xenon headlamp started acting and eventually died, it needed a new bulb and the supporting electronics, when it was finally fixed the total bill came to $1000 including the labor, just one headlight mind you, not bad at all when compared $15 needed to replace the headlamp on my 240D euro-lights.
Soemething to think about, or in my case to avoid on my next car.

Thanks,
Vahe