The W108 and W109 were premièred at the Frankfurt Auto Show in 1965. The initial model lineup consisted of three W108s: 250S, 250SE, and 300SE, as well as a sole W109, the 300SEL. Engines for the new car were carried over from the previous generation, but enlarged and refined.
The W108 included 280S and 280SE, with production starting in November 1967. These replaced the 250S, 250SE and 300SE, however production of export-designated 250S would continue until March 1969. For the W109, the 300SEL finally retired the M189 engine, and received the 280Se's 2.8 M130. In January 1968, the model line was joined by yet another car, the 280SEL. The car had the longer wheelbase of the W109, but lacked the pneumatic suspension and other features of the 300SEL. Hence the chassis code remained W108.