Water pump leaked shortly after purchase. Replaced with new.
Brake master cylinder replaced.
Replaced rear springs as they were sagging a little.
Centre bearing rubber mount on tail shaft replaced.
Opto (?) signal generator to injectors replaced at well over 450,000km.
Interior fan failed... replaced with a used item. Expensive labour costs as dash had to be ripped apart.
Indicator electronic module replaced.
Upgraded to CFC-free refrigerant.
Replaced front disc rotors (at close to 490,000km)
Steering box mounting bolts had worked loose, which meant you could turn steering wheel 90 degrees and car still would go straight. Needless to say I drove home very slowly... fixed next day.
The only time I could say the car let me down was when it suddenly died on the freeway. The signal to the injectors had packed it in, but then the car had covered over 450,000 km.
I'd class other problems as normal wear and tear, and the car was over 20 years old when I had to replace the interior heater fan.
The car was slightly heavy on fuel but servicing was very reasonable from Benz specialist (and also from an authorised repair centre who was absolutely excellent) so overall it really was very reasonable to run.
Beautiful engine and transmission.
Loud car on the highway got a bit wearisome.
Handled reasonably well, rode well though suspension bump-thump irritating (typical Benz according to road reports). Steered well though not sharp at the straigh-ahead.