I don't think we have a majority of the problems, just a majority of the cars. The w124 was one of the most popular chassis MB had built - over 100,000 sold. They are also 6-16 years old, so a pretty good likelyhood that any MB problems are going to be in this model.
I wouldn't mind a seperate forum in many ways, but I would still come to the tech forum - there is just too much cross application between the different models to miss out on something by staying in just a 300E forum. It also might make it harder on the contributing techs like Steve, Benzmac, etc. to have to jump forums and maybe answer the same problem in 2 places for multiple chassis.
Your timing in bringing this up is really good. I had been thinking that maybe the "cars" tab could use a more elaborate sub section under the 300/400/500 E class. The info there is a great introduction, but maybe some sub sections - drawings or photos of the engine compartment with labels for all the parts that we talk about (OVP, ECU, Klima relay, Bowden cable, etc.). A section summarizing some of the more commonly discussed problems and answers. A section for what to look for, strengths, weaknesses, etc, when buying one of these models, that sort of thing.
I have already started reviewing the archives for posts on what to look for when buying (best year, parts uprades like the early 400E brakes, common failures, needed upgrades like larger tires and wheels on 400Es), that sort of thing. I was going to see if Bill Wood could use this as a DIY or supplemental article, but maybe it would fit in with this. Does this approach seem useful at all, or were you thinking of a general forum approach for anything related to 300Es (tires, performance, tech problems, etc.)?
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
Click to see 87 300E