Not easy to find interior pics of these cars... ...unless you know where to look...
#2 The Renault 4CV has got chrome grilles in the air intake, and chrome stoneguards, so it is at least a 1950 Luxe (or 1952+ Affaires or Sport), since older models and the Service and Commerciale didn't have these. The Grand Luxe had 'pullman' seats with a chrome bar on the top. I found that 1956 models had round interior lights, this one must be older. But as far as I could find out, there were no other changes in the interior...
#3 Here is a 1959 300d for sale in Holland. I found in Rétroviseur #53 an interior pic of a 1958 version, but that one had red leather interior...
The 4CV: you have defined the time range, and although the brochure states that there are several interior changes for this year (1954), I am satisfied with your reply. These changes (thinner front seat back rest, increased leg space for the rear seats) they aren't so obvious on a photo.
The Mercedes: sure it's a 300, but not a 1959, and not a 300d (I take it that "D", then as now, is for Diesel. Why a diesel?). The seat pattern is slightly different, I don't know if this due to the year or the model.
The brochure repeatedly states the model name on every page, so I guess the pattern maybe specific. So: forget the year, I'll settle for the exact model.
