Mercedes-Benz M256 engine

The Mercedes-Benz M256 engine is a turbocharged straight-six engine produced since 2017, when it was first introduced on the W222 S 450.^[1] It replaces the previous M276 V6 engine,^[2] and is Mercedes' first straight-six engine since the M104 engine.^[3]

Mercedes-Benz M256
Overview
Manufacturer	Mercedes-Benz
Production	2017–present
Layout
Configuration	Straight-six
Displacement	2.5 L (2,498 cc) 3.0 L (2,999 cc)
Cylinder bore	83 mm
Piston stroke	77 mm, 92.4 mm
Cylinder block material	Aluminium alloy
Cylinder head material	Aluminium alloy
Valvetrain	DOHC 4 valves x cyl
Compression ratio	10.5:1
Combustion
Supercharger	BorgWarner eBooster
Turbocharger	Single-turbo twin-scroll
Fuel system	Direct injection
Fuel type	Petrol
Cooling system	Water cooled
Output
Power output	230–320 kW (313–435 PS)
Torque output	450–520 N⋅m (332–384 lb⋅ft)
Chronology
Predecessor	Mercedes-Benz M276

Design

The M256 shares a modular design with other inline-four and V8 engines, which are all 500 cc (31 cu in) per cylinder.^[4] It uses an aluminium alloy block with dual overhead camshafts and has 4 valves per cylinder.^[5] The M256 uses a 48V electrical system to operate a BorgWarner electric supercharger,^[6] which can spin up to 70,000 rpm to reduce turbo lag.^[7] In the S 500's G variant engine, an integrated starter alternator also provides up to 16 kW (22 PS) and 250 N⋅m (184 lb⋅ft) of boost, and replaces the drive belts by managing the water pump and air conditioning; allowing for a smaller and lighter engine.^[8]

Models

Engine output excluding the additional 48V system boost available on the S 500:^[9]

Engine	Power	Torque	Years
M256 E25 DEH LA GR	230 kW (313 PS; 308 hp) - 270 kW (367 PS; 362 hp) at 5,500–6,100 rpm	450 N⋅m (332 lb⋅ft) at 1,600–4,000 rpm	2021–
M256 E30 DEH LA GR	270 kW (367 PS; 362 hp) at 5,500–6,100 rpm	500 N⋅m (369 lb⋅ft) at 1,600–4,000 rpm	2017–
M256 E30 DEH LA G	320 kW (435 PS; 429 hp) at 5,900–6,100 rpm	520 N⋅m (384 lb⋅ft) at 1,800–5,500 rpm

M256 E25 DEH LA GR

• 2021-present S 400 L/S 450 L (China only)
• 2021-present GLE 450/GLS 450 (China only)

M256 E30 DEH LA GR

• 2017–2020 W222 S 450 / S 450 4MATIC (European models only)^[10]
• 2018–2023 C257 CLS 450 / CLS 450 4MATIC^[11]
• 2019–present X290 AMG GT 43 / GT 43 4MATIC+
• 2019–present X290 AMG GT 50 / GT 50 4MATIC+ (China only)
• 2019–present V167 GLE 450 4MATIC
• 2019–present X167 GLS 450 4MATIC
• 2019–present Austro Daimler Bergmeister PHEV^{[citation needed]}
• 2020–present W213 E 450 4MATIC
• 2021–present W223 S 450 4MATIC
• 2021–present W223 S 580 e 4MATIC

M256 E30 DEH LA G

• 2017–2020 W222 S 500^[12]
• 2018–2023 W213 E 53 4MATIC+^[13]
• 2018–2023 C257 CLS 53 4MATIC+^[14]
• 2018–present X290 AMG GT 53 4MATIC+^[15]
• 2020–present V167 GLE 53 4MATIC
• 2021–present W223 S 500 4MATIC
• 2021–present Aston Martin DBX Straight-Six