I had occasion recently to drive a 2005 CDI for a 115 mile trip. I thought it was a splendid machine. Acceleration was exceptional, and the power was consistent through the whole range of speeds. In no way did it sound like a diesel, which for an old Luddite diesel lover like me was a little sad. It just ran like a high performance car, with so many electronic bells and whistles that it scared me a bit. I doubt that this will be a DIY car, except maybe for oil and filter changes. I have heard that the W211 chassis has been plagued with reliability and quality problems, as has the entire MB line of late. This car, with about 2,000 miles on it, was superb, and the owner said he routinely gets 31-36 mpg.
Settling back behind the wheel of my 1979 300TD (non-turbo) wagon was quite a contrast. It seemed primitive, to be sure, but more accessible. I feel confident that I can deal (and I have dealth with) with many of its mechanical systems in the comfort of my own garage.
I wonder if the CDI will have the longetivity of the old OM 615, 616, and 617 engines. Anyone with experience, or an opinion, chime in.
Joe B.