2020 MERCEDES-BENZ CLS-Class M256 (mild-hybrid inline-6)/M177 (V8 biturbo) (C257)
C257 / 4-door coupe / Global (including Europe, North America, China, Middle East)
M256 (mild-hybrid inline-6)M177 (V8 biturbo)Exact year/trim recordSilver
Engine identity
Oils and fluids
Service and parts data
Common and chronic problems
- Potential air suspension issues over time
- High pressure fuel pump wear in early M256 variants
First checks
- Verify adaptive suspension operation
- Inspect turbocharger boost sensors
- Check electrical system for mild-hybrid components
Before replacing parts
- Save fault codes and freeze-frame data before clearing anything.
- Check engine oil, coolant and transmission fluid using the correct temperature and service procedure.
- Verify power, ground, connectors, hoses, leaks and live data before replacing expensive parts.
Important notes
- Market-dependent engine availability: diesel offered primarily in Europe and regions with diesel demand; petrol and AMG models global.
- M256 features integrated starter-generator mild-hybrid system improving efficiency and torque.
- Oil capacity includes service-fill quantity and filter replacement; always confirm exact current specs with Mercedes-Benz service literature.