My friend has the W124/125 first model, 250D, with the super 5 cylinder diesel engine: OM 602.912 https://en.wikipedia.org/wiki/Mercedes-Benz_OM602_engine

It's not just a beauty, is working super fine: and never stops. They made the 200D, 250D, 300D with the same engine, just adding one piston.

My friends comes and go from the EU to Turkey (5.000 km) with no issues at all: on the way he stops at a Turkish dealer of auto parts www.brossautoparts.com where he is able to just get the little plastic parts they get ruined (one was a little plastic wheel on the mileage meters they gave him for free 3 months ago).

In the second hand marked you can find this car for 4.000€ which is a totally ridiculous price !

He told me about the right and left mirror, which are not symmetric: Mercedes made a long research on usability and efficacy on mirrors, and discovered the right mirror can and should be smaller and squared (and, of course, remote controlled), while the left mirror was surprisingly preferred controlled by hand, so there is just a stick of metal (a rudimentary joystick) the driver can hold and move.

The sad is that he told me the second and third series had issues (as somebody else wrote already above) with metals, with the plastic on the side, and unfortunately with the electrical wiring (replaced with a more Eco-friendly version which did not last more then 10 years).

Let's remember the designer: the Italian Bruno Sacco, who had to fight a bit to have the new design accepted: the change from w123 to w124 was a big risk, and they made a test with the Mercedes 190 (a smaller version of the w124): which was a great success of the 80s (the coolest car a youngster could have in Italy at that time).

Yes, it is sad that no factories would consider such a good quality product nowadays: I remember what the famous marketing professor Kotler once told Philips and Braun about their reliable electric razors: "So, you find a customer who buys your razor, and then you make it so reliable that he won’t need another one for the next 40 years? Are you crazy?"