The Mercedes-Benz M120 V12 engine used in the 600 SEL had a displacement of 6.0 liters.
More precisely, the M120 E60 displaced 5,987 cubic centimetres, conventionally rounded to 6.0 litres. It was a naturally aspirated 60-degree V12 with dual overhead camshafts and four valves per cylinder. Mercedes-Benz introduced it in 1991 for the W140-generation 600 SE and long-wheelbase 600 SEL, then used related versions in other flagship models.
The engine was engineered as Mercedes-Benz’s answer to the growing prestige of BMW’s V12-powered luxury cars. In the 600 SEL, it delivered about 300 kW in some specifications and roughly 570–580 Nm of torque, giving the large S-Class strong high-speed performance despite its substantial size and weight.
A common mix-up is treating the badge’s “600” as an exact displacement figure. The badge is a model designation, while the engine’s measured capacity is 5,987 cc. The M120 later powered the 600 SEC, 600 SL and 600 SL, before being replaced in Mercedes-Benz’s S-Class range by the smaller M137 V12.