The Mercedes-Benz M256 engine is a turbocharged straight-six engine produced since 2017, when it was first introduced on the W222 S 450. It replaces the previous M276 V6 engine, and is Mercedes' first petrol-powered straight-six engine since the M104 engine.
The M256 shares a modular design with other inline-four and V8 engines, which are all per cylinder. It uses an aluminium alloy block with dual overhead camshafts and has 4 valves per cylinder. The M256 uses a 48V electrical system to operate a BorgWarner electric supercharger, which can spin up to 70,000 rpm to reduce turbo lag. In the S 500's G variant engine, an integrated starter alternator also provides up to and of boost, and replaces the drive belts by managing the water pump and air conditioning; allowing for a smaller and lighter engine.
Engine output excluding the additional 48V system boost available on the S 500:
2018âÂÂ2023 C257 CLS 450 / CLS 450 4MATIC