I could be full of it, but IMHO it is the 114/115 with which MB really made its name as a purveyor of fine cars that could be owned by the general public. (I.e., not 600's or Maybachs and that sort. Or even S's or SL's.) They made a bunch of them, which paved the way for 123/4's, 201's, C & E classes, etc.
-- Jim
