I bought this car for my father 10 years ago from the first owner (kind of like a company car) who took good care at the dealer.
The first thing we had to deal with was the hard cold/hot starting. After a few weeks of testing, we tried with 4 new injectors (around $20 each), and the problem was solved. As a matter of fact, even the torque at the low end improved. No problems since.
Change the synchros of the manual gearbox 6 years ago by an specialist (around $300), it has been working flawless.
In those ten years, we had to change 2 fuel pumps (around $100 each), A/C tensioner pulley once ($20) and belts, lower suspension and steering ball joints around ($200 for all), radiator ($200), and of course the usual tune-up maintenance (filters, spark plugs, cap distributor once, brakes) and that´s it.
The engine pulls strong, does not smoke, uses around 1 quart of oil every 2000 kms. Last year we changed the valve seals (around $20 for parts) to reduce the oil consumption. It improved somehow.
A couple of years ago I bought (in the USA) some square feet of the original Sienna color MB TEX vinyl (yes, it is available in USA, it had printed on the back "made in Germany") and a carpeter rebuild the whole driver seat: it looks like new, exact color.
It is starting to rust now under the floor and on the rear wheel arches.
This Mercedes has been running on Costa Rica´s crappy roads (full of potholes and bumps) for almost 28 years and I am amazed how solid this car feels and looks. All panels are aligned as the day it left the factory, the interior is almost flawless: just the carpets looks a bit used, the dash and doors panels look like new.
The only issue is regarding the awkward driving position: all pedals feels too far away, but the steering wheel way to close, and both front seats to low. This car was probably designed for taller people...
The engine in quite adequate for this chassis, and the fuel consumption is reasonable, even for today standards.
Overall, this is a fantastic car that gave Mercedes its reputation, now diminished by quality issues with the new models.