The top models of the CL, G, S, and SL models, such as the G65, S65, or SL65, are equipped with the 6.0-liter 12-cylinder Mercedes M279 engine, which was first introduced in 2012. This power unit comes in two variations: AMG for 630 horsepower and stock for 530 horsepower.

M120, M137, M275, and M279 are members of the V12 family.
Specifications
| Production years | since 2012 |
| Displacement, cc | 5980 |
| Fuel system | distributed injection |
| Power output, hp | 530 (M 279 E 60 AL) 612 – 630 (AMG M 279 E 60 AL) |
| Torque output, Nm | 830 (M 279 E 60 AL) 1000 (AMG M 279 E 60 AL) |
| Cylinder block | aluminum V12 |
| Block head | aluminum 36v |
| Cylinder bore, mm | 82.6 |
| Piston stroke, mm | 93 |
| Compression ratio | 9.0 |
| Features | no |
| Hydraulic lifters | yes |
| Timing drive | chain |
| Phase regulator | no |
| Turbocharging | Biturbo |
| Recommended engine oil | 5W-30 |
| Engine oil capacity, liter | 10.5 |
| Fuel type | petrol |
| Euro standards | EURO 5/6 |
| Fuel consumption, L/100 km (for Mercedes AMG S65 2017) — city — highway — combined |
19.9 10.9 14.2 |
| Engine lifespan, km | ~270 000 |
| Weight, kg | 280 |
The engine was installed on:
- Mercedes CL-Class C217 in 2014 – 2019;
- Mercedes G-Class W463 in 2012 – 2018;
- Mercedes S-Class W222 since 2014;
- Mercedes SL-Class R231 in 2012 – 2018.
Disadvantages of the Mercedes M279 engine
Dual coils have finally eliminated the need for pricey ignition blocks.
The engine has no coking issues because of the distributed fuel injection.
The sleeve of such a unit after scuffing has already been reported on specialized forums.
Owners have also complained about the timing chain being stretched up to 150,000 kilometers.
