AMG's Long-Cherished, In-House Designed and Produced "M156" V8 Unit

Improving environmental performance is an urgent challenge for automakers. Especially in Europe, where the implementation of tiered regulations, which link excessive CO2 emissions to heavy penalties, begins this year, efforts toward better fuel efficiency are more critical than in Japan. Indeed, you are likely aware that cars arriving from Europe routinely tout efficiency improvements of 10-20% over their predecessors.

This trend is unavoidable even in the world of high-performance cars. Even Ferrari is now implementing idle stop systems across its entire lineup. While fuel economy can fluctuate by 10-20% depending on the driver's awareness, this has become a responsibility that brands must bear, both financially and in terms of compliance.


AMG, which had long served as Mercedes' tuning constructor, became a subsidiary of Daimler in the late 1990s and has continued to develop high-performance models in parallel with the development of production vehicles.

In this process, they obtained their own long-cherished, in-house designed and produced V8 unit in 2006. The M156, despite its large 6.2-liter displacement, was a high-revving, high-output naturally aspirated engine capable of exceeding 7000 rpm without being hindered by the mass of its moving parts. For a time, it was deployed in almost all AMG models.

The M156 Unit Steps Down from its Leading Role

However, the M156 has now retired from its leading role, and the engines installed in AMG models are sequentially being replaced by the 5.5-liter twin-turbo M157. The reason, above all else, is improved environmental performance. The M157, incorporating the latest turbo and direct injection technologies, has achieved a remarkable 28% improvement in fuel efficiency in the most recent ML63 AMG model, even when combined with the idle stop system. As this example shows, the high-efficiency evolution of internal combustion engines by European manufacturers has dramatically advanced even within the last five years.


With the full model change of the SL class now announced, the AMG lineup featuring the M156 is effectively limited to this C63. If we broaden the interpretation slightly, the SLS, AMG's pure sports car, is powered by the M159, a special unit that underwent thorough mechanical tuning based on the M156.

Or, from a chronological perspective, one could argue that the M156 was a detuned version of the power unit developed for the SLS, adapted for regular models. If this is crammed into the compact body of the C-Class, it's enough to make any car enthusiast's heart race.

The Elements Defining the C63's Character

Still, why does AMG continue to equip only the C63 with the M156? I had the opportunity to speak with an AMG executive in charge of vehicle development recently and asked about the true intention. However, from him, whose urgent priority is improving environmental performance, I could not elicit an affirmative response. So, as a personal opinion, I conveyed that I believe the SLS and C63 are icons of AMG's dynamic performance, to which he smiled and nodded.

His words were not mere politeness; the C63 stands out in terms of dynamic performance among AMG's recent products. While the approach is traditional, the tuning was quite aggressive in the early models, overturning the image of a "fast and furious gentleman's saloon" that preceded it. Although the ride has become somewhat milder after several refinements, the unwavering commitment to dynamic performance remains unchanged. And with the major facelift of the base model, the C63 lineup has been refreshed, with the addition of a coupe to the existing sedan and wagon. This further clarifies its position as a sports model.


There are two elements that define the C63's character. The first is the aforementioned M156 unit. Its abundant torque, stemming from its large displacement, powerfully propels the small body from a standstill. The sensation of acceleration is, as expected, richer and more profound compared to a turbo unit with equivalent power. As it approaches the high-rev range, you can experience the thrill of precision parts connecting seamlessly. If the true pleasure of a naturally aspirated engine lies in its raw responsiveness, unlike turbo units that urge the revs up as if rushed by boost, then the M156, in a package usable for daily driving, can be considered its pinnacle.

A Future Classic That Will Be Remembered

The second element is the chassis. As mentioned earlier, due to repeated refinements, the ride comfort itself has had its sharp edges, which could be uncomfortable for occupants in the early models, neatly rounded off. Nevertheless, compared to the standards of its peers, the setup is firm, and those who have experienced recent AMG models with their smooth ride, comparable to the standard versions, might find it slightly jarring.

However, the impression changes dramatically once you enter the highway. The car's ability to glide over bumps and the steering feel that faithfully transmits road conditions, while retaining the inherent Mercedes smoothness, create a sense of stability that becomes more pronounced the faster you go. Even when encountering large bumps, the excellent suspension control quickly settles the car, effectively minimizing body movements and consequently limiting physical stiffness caused by eye strain.


Its composed behavior in corners is ideal for confident and enjoyable street driving, but even at track speeds, it doesn't exhibit any embarrassing understeer. The fundamental rear-wheel-drive cornering manner, which involves transferring driving force to the rear axle to change direction quickly, is beautifully balanced with the immense power available from anywhere.

Driving the C63, with its exquisite body size perfect for urban use, might remind older car enthusiasts of the legendary 500E. Released in the early 90s, that car was an unparalleled sports sedan, set up in the Mercedes tradition with practicality as the utmost priority.

Furthermore, the C63 possesses the charm of the internal combustion engine that we have cherished and admired. The pleasure of operating such an engine, which is becoming difficult to obtain in today's efficiency-first era, should be maintained through individual awareness and responsibility. For the many car enthusiasts who will continue to seek a compromise between personal enjoyment and social responsibility, the C63 will undoubtedly become a future classic that will be remembered.