I have read at various points over the years that MB started subtly cheapening various aspects of the 124 during its production. This effort started in the 1991 time frame, and started becoming phased into production in 1992 models, and definitely by the 1993 and 1994 models.
This was at the point of the switch-over to when MB was starting th design cars to a cost point, and exactly the time when the w210 was being designed.
Because the W124 was already 2/3 into its production life, there was little that could be done other than subtly reducing costs. The 202 and 210 (and W140 after its second or third year of production) were the first models that were designed and built to cost points — and in the case of the W140, NOTICEABLY de-equipped and having things costed out.
Anyone who knows W140s will tell you immediately that there are major and noticeable differences between a 1992 or 1993 W140 and say, a 1995 or 1996 W140.
As said this cheapening not only entailed omitting or reducing some previous finishing of parts (think the silver lettering on M119 air boxes being gone by the mid-1993 time frame) but also indeed subtle changes in things like metal thickness, interior materials quality and the like. Remember that US 1992 models used a leather owners manual pack; 1993-1995 USA cars used a faux leather manual pack.
Even the MB-Tex of say a 1990 or 1991 W124 is very different than that of a 1994 or 1995 model. The carpet also had subtle differences, too. This started noticeably changing for pedestrian models in the 1992 time frame.
I owned 1992 and two different 1995 124 wagons and there was a solidity and ethereal quality difference between them that I could discern, but never truly put my finger on.
The E500E was largely unaffected because it was the premium model in the lineup, and had the best of everything (ie leather or cloth Recaro seats). I do think there are slight differences in the body materials/sheet metal between the early 1991 and 1992 and later 1993 and 1994 E500Es, but no differences in the interiors and equipment. It’s not really been discussed here because the interiors are the same through production and I believe mask the cheapening. Plus we all know the production processes were top notch and always done by hand. Money was no object with the E500E through its production life.
It’s kind of similar to the W211 and W212, which are NOTORIOUS for having driver’s seats rip and split and just show major wear after just a few years. The AMG variants of these cars didn’t have this seat quality issue because they used top of the line leather seats with a different design and much better materials. Same with the alcantara headliners vs. pedestrian non-AMG cars headliners.
