In January 1976, were "Stroke Eight" series W 114/115 models of replaced by a completely redesigned series with the internal designation W 123rd The model ranged from 2.0-liter four-cylinder diesel with 55 hp to the 2.8-liter six-cylinder injection engine with 185 hp.
Technically, the new model is focused on the production since half years S-Class; how those possessed the new middle-class types on a semi-trailing arm rear axle, which had been already introduced "Stroke Eight" models in, and a double-wishbone front suspension with steering offset 0. This also represented the subframe still used in previous models , The numerous other security-related construction details that had first realized in the series 107 and 116 came, of course, now the middle class types benefit. Most important improvement over the predecessor series was the even more robust safety passenger cell with stiffened roof-frame structure, high strength roof and door pillars and reinforced doors. The energy absorbing front and rear crumple zone could be increased significantly by controlled deformability of front and rear areas.
A technical novelty presented a first realized in the 123 series version of the safety steering column, were connected at the steering unit and the casing tube through a corrugated pipe together. This corrugated pipe which in case of impact also could buckle side, the product may enter the steering column has been further reduced in the car interior.
A characteristic design feature of the new models were the differently sized dual round headlights; next to the headlight was under a common diffusion plate, a smaller halogen fog lamps. Deviating from this, were the two top models in the series, the 280 and 280 E, equipped with rectangular halogen headlamps broadband. From the outside, both 2.8-liter types differentiated but still three other ways from their less powerful brothers: Both 280 as 280 E had a twin exhaust system with twin tailpipes, chrome air intake grille in front of the windscreen and one additional chrome bar below the rear lights.