The fact that the Type 300 is primarily associated with the name of the first Federal Chancellor and is known in the vernacular as "Adenauer-Mercedes" in the classic car scene is due to the fact that "the old man" placed special emphasis on it, only chauffeured in the 300 and always wanted to have his company car with him even when traveling abroad. During his tenure as Federal Chancellor until 1963, and then until his death in 1967, Adenauer used a total of six different 300s. His first company car from 1951 can be admired today in the "House of History" in Bonn, while the car he used in retirement, a 300 d from 1959, became the property of Daimler-Benz in 1967 and has since been in the Mercedes Benz Museum is on display.

The body of the 300 d was clearly modernized, particularly in the roof and rear areas; The filigree design of the C-pillars made it possible to increase the window area by a total of 30%. The 300 now had a "post-free full-view body", which allowed the side window areas to be opened completely, and was accordingly also referred to as a hardtop sedan. The trunk volume was increased by 15% compared to the 300 c by redesigning the rear area.