>>28608222
>W210
No. In fact this was the last car before the DaimlerChrysler merger. The last true benz! Designed before the merger, and built (up to 1999) by Daimler Benz AG, which then ceased to exist forever.
Other than rust problems caused by a bacteria in the paint (which were later rectified), the W210 is one of the most reliable benzes out there.
To answer the OP, the downfall started with the DaimlerChrysler merger. That's when the company stopped being driven by engineers and started being driven by accountants. Before the merger, "Mercedes-Benz" meant "bullet-proof reliability" and "perfection in suspension, braking, engines and ergonomy", afterwards those were not the same criteria anymore.
Nowadays "mercedes" = "luxury thing we can sell with features on par with Audio and BMW", not much than that.
Before the merger, a Mercedes looked like a Merc and not like other car. Now they look like japanese cars.
It really began there and they haven't recovered yet.