I had a late 2003 C200K Merc wagon (Estate) for four years bought from new that was a brilliant car. If I were to complain about anything at all it was that the automatic was too soft and slushy. In every other respect, a great car. Stayed as tight as new throughout its whole life, and I took a 45% residual on the lease (you call it a balloon payment I think) and I still sold it privately for $5,500 more. Being a wagon helped that though - the sedans are more common and not quite as high resale value here in Australia.
Additionally, I drove a E320 wagon for a couple of weeks in Germany whilst at a trade show, and then up through Holland, across the channel and a little bit around the middle of England. It was about a 2003 or 2004 as well and a great drive. Belonged to a business friend and we shared the driving.
In both cars I was able to sit in the seats much longer without squirming or getting a sore back on long drives of several hours and being an ex-mechanic I have a poor back from many years of leaning over bonnets and shimming under cars.
Never had a single warranty problem.
It used to be said that mercs do things so well that you don't know they're doing it. I'm a fan of that.
The only reason I didn't get another one was that we decided to add a second story to the house and so I purchased a cheap RAV4 instead, which I later gave to my son and bought the 1994 525i Touring I have now (which was also at a too-good-to-refuse price).
best regards.