It took European manufacturers slightly longer than GM's major American competitors to produce four-door hardtops (Ford and Chrysler marketed theirs for 1956). Today's subject is the Mercedes-Benz 300d (werknummer W189) launched in August, 1957.
The W189's Wikipedia entry is here. I wrote about the closely-related W186 large Mercedes 300s here.
About 3,100 W189s were produced 1957-1962. Their styling was close to that of the W186s, aside from the "pillarless" feature. Unless noted, the images below are factory-sourced photos.
A 1960 W189 with windows rolled up. Aside from the thin, chromed pillars, it looks much like W186 sedans.
Probably an early W189 at a factory photo shoot. Here all the windows are rolled down, creating a large, open expanse below the roof.
Another rolled-down view, this with a driver and four smiling passengers.
Side view of the lakeside W189. The open window area creates a somewhat lithe appearance for what otherwise is a fairly heavy design. I wonder how the structure would respond in a rollover accident.
Now for two Hyman photos of a 1960 W189. Here only the door windows are rolled down. The aft windows could either be rolled down or remain upright.
This is more clearly seen in this rear quarter view.
Now to place the W189 in context. This is a 1955 Oldsmobile Supper 88 Holiday four-door hardtop, one of the first General Motors offerings. Note that the aft side window is a clean, one-piece affair when rolled up. No extra vertical elements as in the W189 or the Chrysler Corporation example below.
1956 DeSoto Firedome Seville, Mecum auction photo. Chrysler four-door sedan aft doors were not shaped so as to allow retraction of one-piece window glass. So a quarter window was necessary, and Chrysler engineers had to come up with a means of retracting it along with the main window.
The result as seen in this for sale '56 DeSoto Firedome worked, but was awkward appearing when the windows were partly lowered. Mercedes' quarter-window solution was better.