Mercedes is one of the few manufacturers, alongside Rolls Royce, that still uses a V12 engine in its limousines. The V12 engine has survived only in the Mercedes-Maybach S 680 and in Rolls-Royce Ghost and Phantom limousines because Audi A8 and BMW 7 Series does not features anymore a V12. Here, we present a history of modern Mercedes V12 engines.
The M120 Engine
In 1991, Mercedes introduced the M120 V12 engine as a response to BMW’s M70 V12, which was launched in 1987. While BMW’s engine produced 300 PS with a 5.0-liter displacement, Mercedes’ M120 delivered 408 PS and 580 Nm of torque with a 6-liter displacement.
The M120 was a naturally aspirated engine with an aluminum engine block and cylinder head, a 60-degree angle between the cylinder banks, four valves per cylinder, sequential fuel injection, and forged steel connecting rods.
The M120 V12 engine was used by Mercedes from 1991 until 1999 when production ceased due to emissions regulations. It debuted in 1991 under the hood of the Mercedes 600 SE/SEL W140 and was used from 1992 in the 600 SEC/S 600 Coupe/CL 600 (C140) coupe and the 600 SL/SL 600 (R129) roadster.
Initially, it produced 408 PS and 580 Nm, but after the 1993 facelift of the S-Class – renamed S 600/S 600 L – its power and torque were reduced to 394 PS and 570 Nm.
This engine was the foundation for high-performance developments.
The M297 version was derived from the M120 and had a displacement of 6.9 liters, achieved by increasing the piston stroke from 80.2 mm to 92.4 mm. It was used exclusively in the 25 units of the CLK GTR and developed 631 PS.
An enlarged bore version –from 89 mm to 91.5 mm – was found in the Pagani Zonda up until 2016.
The M137 Engine
In 1998, a regression followed. The previous generation S-Class (W140) was very heavy, and the M120 V12 engine contributed to the excessive weight.
That’s why Mercedes designed a lighter and more compact V12 engine, though also less powerful.
Like the M120, the M137 was a naturally aspirated V12 engine with a 60-degree V angle, 5.8 liters in displacement, and 80 kg lighter than the former M120. Compared to the M120, the M137 was an almost square engine (bore x stroke 84 x 87 mm) and featured a cylinder deactivation system. It also had a different distribution system with three valves per cylinder -two intake and one exhaust, and only one camshaft per cylinder bank instead of four valves per cylinder and two camshafts per cylinder bank.
It was used in the S 600 (W220) and CL 600 (C215).
This engine also had a performance version named M137.980, with increased displacement to 6.3 liters (bore x stroke 84.5 x 93 mm). It developed 443 PS and was available in a very limited series in the S 63 AMG (only 70 units), CL 63 AMG (only 26 units), and the G 63 AMG (W363).
The M275/M285 Engine
In 2002, Mercedes decided to abandon the naturally aspirated engine and switched to turbocharging. The new M275 V12 engine featured two turbochargers and two intercoolers but retained the 60-degree architecture and the solution of three valves and two spark plugs per cylinder.
With a displacement of 5.5 liters (bore x stroke 82 x 87 mm), the V12 engine developed between 500 and 517 PS. It powered the S 600 (W220) after the 2002 facelift, the CL 600 (C215) after the 2003 facelift, as well as the new S 600 (W221) from 2005, CL 600 (C216) from 2003, and SL 600 (R230) from 2003.
The M275 AMG version had its displacement increased to 6.0 liters (bore x stroke 82.6 x 93 mm) and developed between 612 and 670 PS. It was used in numerous AMG models such as the S 65 AMG (V220), S 65 AMG (V221), CL 65 AMG (C215), CL 65 AMG (C216), SL 65 AMG (R230), SL 65 AMG Black Series (R230), G 65 AMG (W463), and even the limited edition Maybach G 650 Landaulet (W463).
The M285 version, similar to the M275, was found under the hood of Maybach models, while the sporty Maybach 57S and 62S used the M285 AMG version with 6.0 liters of displacement, directly derived from the M275 AMG.
Mercedes also developed a special series called M158, derived from the M275 AMG, specifically for Pagani. The 6.0-liter engine was developed from 730 PS upwards and was used in the Pagani Huayra and Utopia.
The M277/M279 Engine
In 2012, Mercedes introduced a new generation of V12 engines that is still in production today and is found under the hood of the current Mercedes-Maybach S 680. Although it retained the solution of three valves per cylinder and a single camshaft per bank of cylinders, Mercedes made many modifications:
- increased the displacement to 6.0 liters
- added forged pistons and a forged crankshaft
- new ignition system
- new engine control unit
- new camshafts
- sodium-cooled valves
The V12 engine was initially paired with the 7G-Tronic automatic transmission and developed 530 PS. Later, the M279 AMG was developed, which features new turbochargers, new exhaust pipes, and a new cylinder head, leading to an increase in power to 612 PS. This engine version is currently used in the Mercedes-Maybach S 680 mated with 9G-Tronic automatic transmission and 4Matic all-wheel drive for the first time.
