A final model was added in August 1969, the 280 SE 3.5. The car was fitted with the brand-new M116 3499 cc V8 engine with 200 hp (150 kW) at 5800 rpm, a top speed of 210 km/h (130 mph) (205 km/h (127 mph) with automatic transmission) and a 0-100 at 9.5 seconds (11.5 for the auto).
To accommodate the large engine, the car's front grille was widened and front and rear bumpers were modified with the addition of rubber strips. The rear lenses changed to a flatter cleaner design. This change was carried across the standard 280 SE. Some view this car as an ideological successor to the W112 300 SE, though it lacked the air suspension of the W112.