Mercedes-Benz CLS engines

Since its launch in 2004, the Mercedes-Benz CLS has established itself as the founder of the four-door coupé segment, offering a diverse Mercedes-Benz CLS engine range across three generations. Each generation has brought innovative technologies and different approaches to performance and efficiency, with technological evolution ranging from classic V8 engines to modern mild-hybrid systems.

Mercedes-Benz CLS Generation I (2004-2010)

The first Mercedes-Benz CLS generation was a pioneering period for the four-door coupé concept and was characterized by powerful but thirsty engines. Mileage varied greatly depending on the engine type: while the tried-and-tested V6 petrol engines easily reached 250,000 to 350,000 kilometers with proper maintenance, the V8 engines often required costly repairs to the air suspension or electronic components between 150,000 and 200,000 kilometers. The Mercedes-Benz CLS engines of this generation were not yet optimized for efficiency, but instead relied on classic naturally aspirated engine technology. The absolute top engine of this generation was the CLS 350 with 272 hp, which optimally combined power, reliability and relative economy and is considered the most reliable engine of the first generation.

Mercedes-Benz CLS petrol engines: Generation I (2004-2010)

The Mercedes-Benz CLS petrol engine range consisted exclusively of naturally aspirated engines with different numbers of cylinders. It started with the CLS 280 (M272, 231 hp), followed by the popular CLS 350 (M272, 272 hp) and the powerful CLS 500 (M113, 306 hp). These Mercedes-Benz CLS engines suffered from typical problems of the Mercedes generation of the time: solenoid valves for camshaft phasing, oil loss due to porous seals and, in the case of the V8 engines, occasional problems with the cylinder head gasket. The most powerful Mercedes-Benz CLS was the CLS 63 AMG with 514 hp from a 6.2-liter V8 (M156), which offered impressive performance but was also considered the most maintenance-intensive engine of this generation. The camshaft adjustment and the head bolts in particular proved to be weak points.

Mercedes-Benz CLS diesel engines: Generation I (2004-2010)

The Mercedes-Benz CLS diesels were initially available with the CLS 320 CDI with 224 hp (OM642), which was introduced in 2005. This was later followed by the more powerful CLS 350 CDI with 265 hp, also based on the proven V6 diesel OM642. The Mercedes-Benz CLS 320 CDI developed into the most reliable diesel of the entire generation - especially the variants produced from 2006 onwards with revised common-rail injection proved to be very durable and economical. These Mercedes-Benz CLS CDI engines offered an excellent combination of torque, consumption and reliability, with occasional problems with the particulate filter and EGR cooling.

Mercedes-Benz CLS Generation II (2010-2018)

The second Mercedes-Benz CLS generation marked the transition to modern turbo technologies and is considered the most technologically advanced generation of its time. Most engines of this generation can easily reach 200,000 to 300,000 kilometers with proper maintenance, whereby the V6 diesels with BlueTEC technology are considered to be particularly durable. Major engine failures have become rarer, but the new turbo petrol engines have shown occasional weaknesses in turbochargers and high-pressure pumps. The absolute highlight was the CLS 350 CDI with 265 hp - a technical masterpiece with BlueTEC exhaust gas purification that offered both power and efficiency. This generation also introduced the first hybrid approaches and set new standards in comfort and technology.

Mercedes-Benz CLS petrol engines: Generation II (2010-2018)

The Mercedes-Benz CLS petrol engine range was completely revised and included both naturally aspirated and turbocharged engines. It started with the CLS 250 (M274, 211 hp), a 2.0-liter turbo, followed by the CLS 350 (M276, 306 hp) with a naturally aspirated V6 engine. These smaller Mercedes-Benz CLS TSI engines proved to be significantly more efficient than their predecessors, with only occasional problems with the high-pressure pump. For sporty drivers, there was the Mercedes-Benz CLS 500 with 408 hp and the CLS 63 AMG with up to 585 hp, the latter being used in the CLS 63 S. However, the Mercedes-Benz CLS 500 (M278) developed into the most problematic engine of this generation, with frequent reports of turbocharger damage and problems with the timing chain at high mileages.

Mercedes-Benz CLS diesel engines: Generation II (2010-2018)

The Mercedes-Benz CLS CDI was offered in various power levels from 204 to 350 hp. The tried-and-tested OM642 was used in the CLS 250 CDI (204 hp), CLS 300 CDI (245 hp) and CLS 350 CDI (265 hp). The powerful CLS 400 CDI with 340 hp was also available. All Mercedes-Benz CLS diesels featured modern BlueTEC technology with SCR catalytic converter and particulate filter. The Mercedes-Benz CLS 350 CDI proved to be the most reliable and efficient engine of this generation, with a test consumption of just 6.2-7.1 liters per 100 km and high reliability - ideal for long-distance driving and prestigious trips.

Mercedes-Benz CLS Generation III (2018-today)

The current Mercedes-Benz CLS generation relies entirely on electrification and represents Mercedes' vision of the future for luxury coupés. All petrol engines are now equipped with 48-volt mild hybrid technology, while the plug-in hybrids offer impressive electric ranges. Long-term experience shows promising approaches, although the first few years were still characterized by teething troubles. The top-of-the-range engine is the CLS 53 AMG with 435 hp, which combines sporty performance with relative efficiency. The mild hybrid technology promises a service life of over 250,000 kilometers, as the electric assistance relieves the combustion engine. Typical repair intervals are 120,000-180,000 kilometers for major maintenance work, although the complex electronics occasionally require earlier intervention.

Mercedes-Benz CLS mild hybrid petrol engine: Generation III (2018-today)

Two engines form the basis of the Mercedes-Benz CLS engine range: the CLS 350 with 299 hp (M256) and the CLS 450 with 367 hp (M256). Both Mercedes-Benz CLS engines feature 48-volt EQBoost technology with an integrated starter-alternator. The Mercedes-Benz CLS 350 with M256 engine is considered to be particularly successful and is developing into the best engine of this generation - it offers smooth power delivery thanks to electric assistance and has so far been largely free of major production problems, apart from occasional software updates for the mild hybrid system.

Mercedes-Benz CLS AMG engines: Generation III (2018-today)

The Mercedes-Benz CLS AMG variants offer the CLS 53 with 435 hp (M256) and the CLS 63 S with 630 hp (M177). These Mercedes-Benz CLS engines combine power with modern technology, with the CLS 63 S being the most technically complex engine and showing occasional problems with the exhaust system.

Mercedes-Benz CLS diesel engines: Generation III (2018-today)

A Mercedes-Benz CLS 350d with 286 hp (OM656) is available and continues the tradition of reliable Mercedes-Benz CLS diesels. This engine is considered to be one of the most modern diesels ever and has shown excellent reliability values to date.

Conclusion: The best Mercedes-Benz CLS engines of all generations

The development of the Mercedes-Benz CLS engines clearly shows the change from classic naturally aspirated engines to highly efficient mild hybrid systems. While the Mercedes-Benz CLS diesel engines have remained reliable across all generations, the powerful AMG petrol engines have consistently struggled with higher maintenance requirements. The new third-generation mild hybrid technology offers a promising alternative for drivers who value efficiency and modern technology.

• Best Mercedes-Benz CLS petrol engine:

The Mercedes-Benz CLS 350 (299 hp, Generation III) combines modern EQBoost technology with high efficiency and excellent reliability to date.

• Best Mercedes-Benz CLS diesel engine:

The Mercedes-Benz CLS 350 CDI (265 hp, Generation II) offers the best combination of reliability, economy and long-distance capability across all generations.

• Best Mercedes-Benz CLS all-round engine:

The Mercedes-Benz CLS 350d (286 hp, Generation III) with its modern OM656 technology and outstanding efficiency combined with sporty performance.

For maintenance and spare parts for all Mercedes-Benz CLS generations, AUTODOC offers a comprehensive range of original and quality spare parts with fast delivery.

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