Behind the code name M252, Mercedes introduces a new generation of gasoline engines designed to combine efficiency and performance. This 1.5-liter four-cylinder block, mounted transversely, has been optimized to meet the requirements of the brand’s compact architectures, particularly in the upcoming Mercedes CLA, GLA and A-Class.
It’s based on a Miller cycle, a variant of the Otto cycle that favors a high compression ratio and early intake valve closing. This choice helps reduce thermodynamic losses and improve overall efficiency. The result: versions producing 136, 163 or 190 horsepower depending on the variant, with decent performance but especially impressive fuel consumption figures of around 4.6 L/100 km (51 mpg) according to preliminary data.
The M252 block belongs to the modular FAME (Family of Modular Engines) platform, a common base for Mercedes’ new generation of internal combustion engines. It aims for an optimal balance between cost, compactness, efficiency and electrical integration.
48V Mild Hybridization: Toward Soft but Strategic Electrification
Rather than switching entirely to plug-in hybrid or full electric, Mercedes is betting here on 48V mild hybridization, integrated almost invisibly into the vehicle’s operation. Thanks to an alternator-starter connected to a small lithium-ion battery, the combustion engine can shut off more often, restart discreetly, and even provide a small electric boost at low speeds.
This system also enables energy recovery during braking, extends coasting phases and reduces consumption peaks in city driving. It doesn’t allow for extended all-electric driving, but improves overall efficiency without imposing the complexity of a full hybrid system.
In the US market, this solution remains relevant in a context where non-plug-in models maintain stable demand, especially in corporate fleets and among consumers wanting a compromise between combustion and light electrification.
A Mercedes Engine… But Made in China
This is probably the information that will generate the most reaction: the M252 engine isn’t assembled in Germany, but rather produced in China. Specifically, its manufacturing is handled by Horse, the entity co-owned by Geely, Renault and other partners, with Mercedes as a client in this particular case.
This choice isn’t random. It allows Mercedes to reduce production costs and ensure rapid scaling for combustion engines still present in its lineup. The M252 thus illustrates a growing trend among European manufacturers: outsourcing certain combustion blocks to Asian partners, while keeping design, calibration and software integration in-house.
The case of the M252 engine in the upcoming Mercedes CLA mild hybrid is emblematic of this strategy: a European car, designed in Stuttgart, but equipped with a highly efficient combustion engine… made in China.
What to Expect in Terms of Fuel Economy and Driving Experience?
Preliminary data announces a combined fuel consumption of 4.6 L/100 km (51 mpg), which would place this engine among the most efficient in the non-plug-in gasoline category. The presence of the 48V system allows reaching these figures without radically changing the driver’s usage, unlike a PHEV that requires regular charging.
Paired with a dual-clutch automatic transmission (7G-DCT type or equivalent), the M252 engine aims for smooth, urban and efficient driving, without targeting sportiness. Performance is sufficient for versatile use, but the positioning is clearly oriented toward efficiency rather than emotion.
This engine will progressively replace the M270/M282 blocks from previous generations, which until now equipped the majority of Mercedes’ compact combustion models. An update made necessary by tightening European standards and new expectations for COâ‚‚ reduction.
A Two-Faced Strategy: Thermal Efficiency and Industrial Refocusing
By betting on a more efficient engine, lightly electrified and produced at lower cost, Mercedes illustrates a dual transition. On one side, the objective is clear: reduce average emissions across its range, while maintaining a competitive combustion offering for markets not yet ready to switch entirely to electric.
On the other, the Chinese manufacturing of the M252 shows a paradigm shift: compact segment combustion engines are no longer strategically “sacred” in Europe. High-performance blocks (AMG type or 6-cylinder) will remain German, but compact engines follow the industrial logic of a globalized and rationalized market.
In the coming years, this type of powertrain could well constitute the transitional offering par excellence: less complex than a plug-in hybrid, more accessible than a pure electric, and efficient enough to remain relevant in the US regulatory context.
