This large Mercedes model was launched in 1951 and became 300D in August 1957, when it received an injection engine and redesigned fenders. Its headlights were also more upright. The “d” here does not mean diesel (it is equipped with a gasoline 6-cylinder), but marks the evolution of the 300, after the 300a, 300b and 300c. This 4-door convertible was produced parallely to the sedan.