The main change was the use of the 2778 cc M130 engine with 170 PS (130 kW; 170 hp) maximum power and 180 lb·ft (244 N·m) maximum torque, which finally gave the W 113 adequate power. The performance improvement was achieved by increasing bore by 4.5 mm (0.2 in), which stretched the limits of the M180 block, and required pairwise cylinder casts without cooling water passages. This mandated an oil-cooler, which was fitted vertically next to the radiator. The M130 marked the final evolution of the venerable SOHC M180 inline-six, before it was superseded by the entirely new DOHC M110 inline-six introduced with 1974 European R107 models.
A brief chronology of the most visible changes made to the 280SL:
- January 1968: One piece wheel-covers (like the W 108 sedans)
- October 1968: US models with sealed beam headlights without fog lights.
- February 1969: New tail lights with amber turn signals.
- July 1969: US models with transistorized ignition and improved emission control.
- August 1969: Heated rear window for hardtop, hazard lights for all models, one unified key for all locks, US models with illuminated side reflectors.
- November 1970: Plastic cooling water header tank (instead of metal). New door locks, cylinder can now be depressed while door is locked.