It's no secret that MB entered a dark era when Jurgen Schremp rose to the top of the company. That's why very few of us here have W210s because we all know they are trouble prone and in general inferior to the W124. I'd love to have those better working headlights, 5 speed automatic, Bosch ME engine management, OBDII diagnostics, and double control arm front suspension, but I know I'd be asking for nothing but trouble if I got one. We ALL know that, that's why we don't have one!
I hear this a lot from W124/W126 owners and I'm sure that W124 owners have heard similar commnts from W123 owners back in the day. I put it down to people's resistance to progress, coupled with Chinese whispers.
Here's my experience with the W210:
I've owned my 1997 E420 for about 10 years on and off. I bought it at around 60k miles, sold it at around 140k miles to a friend and bought it back at 170k miles.
In between the time I sold it and bought it back, I drove a 91 560SEL as my daily driver.
My E420 now has 193k miles. In the last 9 or so years, the most expenisve failure was a catalytic converter that should have been replaced under warranty (but was not).
It it also the spring perch failure which was repaired by MBUSA.
The car had never let me down and the month to month running costs are a
fraction of what I spend on any of my other Mercedes Benz. Furthermore, I put more miles on this car then any of my other cars. When I had the 560SEL as my daily, I rotated it with a US 560SEC, Euro 560SEC and a 6.9 so I put much fewer miles on that car, but spent much more on it.
Aside from known rust issues which don't really exist here in Texas, I don't see any other build quality issues.
My car has 193k miles and always sits outside. It's very presentable for a 16 old car, the leather is crack and split free, the wood still shines and is dark and the paint is still glossy. There is also not a drop of oil on the outside of the engine
I've never owned a W124 but I did test drive a 95 E420 before buying the W210 and it felt old by comparison. I've owned several W126 models which are supposed to be the ultimate Mercedes Benz in terms of build quality. They have had similar mileage to the E420 and while they feel heavier, they wear out faster and do not look as good on the inside or the outside once they reach the kind of miles that my E420 has, unless it's been garaged and coveted.
My E420 is still pretty quick, and will do 24mpg while the A/C freezes you out in a 110 degree Texas summer.
In the 10 years that I have owned it. The only repairs that I've had to do is aside from preventative maintenance have been:
Catalytic converter
Xenon igniters (bought used on ebay)
Transmission conductor plate
Big vacuum line to air mass sensor
Control arm bushings
Spring perch
Blinker stalk
Condenser
Radiator
Auxially fans
Fan clutch
Window regulator on rear window
Tail light assembly (every couple of years)
Blower motor regulator
It's a fairly small list when considering that it spans almost 10 years and 130+k miles.
I still own a couple of W126's along with a few older cars, but I don't think I ever want to go back to driving one daily. The odd thing about this E420 however is that I bought an 02 E55 to replace it and I barely drive that either.
My E420 is now worthless and is only really now starting to show wear and tear on the outside. I don't think that I'll be selling it in a hurry though as it's still one of the nicest driving cars that I own.
These cars are pretty simple and easy to work on, they also pretty reliable. I opted for an 02 E55 as my new modern for that reason. I could have bought a W211 E55 or E550 which are both more powerful, but the complexity of the airmatic suspension, ABC and 722.9 don't make them DIY friendly, and I kind of like to tinker on my own cars.