I'd like to address two points/authors:

W124: There were many differences between US bound cars and other markets' cars. Most of them due to marketing. We could not buy a Mercedes-Benz automobile in the mid-'80s and beyond without: Automatic transmission, automatic climate control, tinted glass, alloy wheels, power windows, power sunroof (for example). There was no cloth interior option, no stickshift even in the SL, no 300SL in the '80s (would have loved one), our options here were quite limited (I sold Mercedes-Benz new in the '80s before returning to college). The reasons were the same as Audi, BMW, Porsche, et al used; market placement and US buyers' expectations. The marketing of a luxury car that had a cloth interior, stickshift transmission, steel wheels and hubcaps, manual windows, and no sunroof would have been too much of a challenge for our salesmen, and too confusing to the general public here to grasp such a concept. In the early '80s, Mercedes-Benz outsold Volkswagen in the state of California, it was the hood-star that has been selling the majority of Mercedes (and Lexus etc.) cars since, and marketing is more important than Engineering. I was an Engineer in the mid-'80s through the end of the millenium, SAE/Automotive, Mercedes was my favorite customer, ... my next-younger brother was Product Planner, All New Vehicles for Lexus, I couldn't understand the decisions that he made but the market loved them. Off my soapbox.

Layback:
I agree with some of your assessment, but don't agree that it is all of the formula that was cooked into the demise of the OM603.97x. I had one. It didn't use oil, but became an organ donor for a project of mine (which is why I bought it). Didn't exhibit any "rod-bending" symptoms. However, when I tore the head off at 237,000miles, I noticed that all cylinders were scuffed significantly, along the sides radial to the wrist pins. The pistons were all level in the bores at TDC. I still have the block, just haven't found the energy to scrap it, but the point is that IMO, the design was inherently less robust than the 3.0L engine due to the longer stroke causing higher crank angles, the lower wrist pins causing still higher crank angles, and the side-forces from these two changes forcing the piston skirts against the walls (both sides BTW, not just compression or just power stroke sides). So although the lower cetain theory has merit, I believe that there are other factors, and as much as I respect your opinion I have to call you and mention that there is no supporting data that proves the cetane and timing relationship conclusively. I don't believe that you intended it to sound conclusive, but it kind of did (to me anyway). Unfortunately, there really isn't enough available data to make such a conclusion. Also, if timing and cetane were the only causes, it seems that there would be many of the 601/2/3/5/6 .5l/cylinder engines around with the same basic design that could be timed a couple of degrees early, and thus suffer the same failure mode.

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Gone to the dark side

- Jeff