My E300D now has 205,000 miles - have replaced some wear items - front ball joints, 1 wheel bearing and the combo switch - but still basicly trouble free. I plan to put another 100k on and hopefully by then the new E320CDI (which is a fabulous car) will be affordable on the used market.
Fuel economy - 30-35MPG always - Reliability - still the best of the 3 diesels I have owned (79 300D, 85 190D). Classic Mercedes lines - all new cars now look like a Ford Taurus - what's up with that?
Still cup holders... back seat room - the S350 diesels of the same vintage are significantly larger. If room is a factor, try to look at one of those too.