I own a '86 Mercedes 250TD W124 with 280 000 kms on the clock. It was repainted last month in its original colour - "Arctic Weiss" - and the engine has been overhauled. It is now in near concours condition and drives like a dream: superb comfort, superb reliability, superb atmosphere and good handling, considering its weight and dimensions.
It's a bit slow - I also own Alfas... but it's kind of a magic - and economical - carpet to travel in style with all the family to the Cote d'Azur every summer... A future classic, without the usual liabilities... Just perfect!
I bought a w124 1989 260e, and I must say it is impeccable! I just changed the oil, and the previous owner had told me that the last oil change before the one I just got on my w124 was about 6 years ago, and that no change was needed since, I was surprised and amazed by the performance of this beauty! I know it will be cherished for many years to come.
My 1989 260E has vacuum lock problems when the weather is exceptionally cold - doors lock on their own poltergeist-like. Also, loud creaks from the suspension in the winter, and cruise works intermittently. In the summer, all the above peculiarities vanish, but then the summer months bring the issue of difficult starting when ambient temps are warm. I think it's the fuel pumps?). The engine will turn readily, but feels like it is not receiving gas, and will cut out. That and the unwillingness of the transmission to kick down speedily are my summer gripes. Still, it is close to twenty years-old, and I suppose I should not expect a perfect car.