Why AMG is risking a 4-cylinder C63

Mercedes Benz C63 S AMG Sedan 2019 1600 15

Halving the flagship C-Class' cylinder count might alienate Mercedes-AMG's loyal customer base, but it involves issues beyond Benz's control. 

The man who built the terrifically successful performance-car business that is Mercedes-AMG (AMG) is also aware of its weaknesses. Since taking control of Mercedes-Benz's Affalterbach-based performance division in 2013, Tobias Moers has used his engineering background to deliver cars that customers want – and generate the kind of profits that the Daimler's shareholders expect.

For the world’s oldest car company, it has been a brilliant business. Since being fully absorbed by Mercedes-Benz in 1999, AMG has become a centre of global technical excellence. Although AMG was once seen as nothing more than wayward tuning firm (prone to creating warranty issues among Mercedes-Benz’s most well-heeled and daring customers), it has inarguably proven its worth.

The downside to growth

AMG has evolved into more than Mercedes-Benz could ever have hoped: It is now recognised as a standalone brand and its models are in high demand. Having said that, there has always been an external risk to the linear progression of AMG’s success – Moers recently alluded to this when he speculated that the division's product line-up had grown too diverse, possibly at the cost of confusing customers and creating the potential for model cannibalisation. 

Political interference is the other significant peril for AMG. As EU and global emission laws grow ever stricter, AMG has realised that its celebrated V8 engines are at risk. The original M156 V8 established the brand’s dominance, but when AMG shrunk its V8 engines from 6.2 to 4.0 litres and added turbochargers, it triggered a trend that was never going to reverse. 

Hybridisation is now a reality for AMG and the latest information from Germany suggests that one of the brand’s most iconic cars is likely to be radically downsized in the W206 C-Class. 

Skipping the sixes

Despite introducing a 6-cylinder AMG in 2018, AMG looks to be pursuing 4-cylinders instead.

After an absence of nearly 20 years, Mercedes-Benz revived its inline 6-cylinder configuration in 2018. It was not a question of respecting tradition, but a decision driven by pure economics and engineering requirements...

Packing the latest mild-hybrid technology, with integrated starter motors and generators proved far easier with an inline engine, as opposed to the more popular V-configuration. 

Mercedes-Benz also gained notable build efficiency by replacing its V6s with inline sixes. A production line that makes inline 4-cylinder engines can easily be adapted to produce 6-cylinder powerplants too. By contrast, building a mix of inline 4-cylinder engines and V6s on a single machining and assembly line is nearly impossible. 

AMG has implemented the new 3.0-litre inline 6-cylinder engine in the 53-series models, but the V8-engined 63s have historically driven a great deal of profit for Affalterbach. 

However, the pressure on AMG's future performance-car business is now so severe that the Affalterbach division is engineering a radical new powertrain structure destined to halve its powerplants' cylinder counts. The next iteration of the C63 is virtually guaranteed to become AMG’s first 63-series car that is not a V8. As a matter of fact, it won’t even be an inline 6…

Numbers or noise?

Mercedes-AMG has built much of its reputation on producing powerful, but also particularly sonorous, V8 powerplants. 

There are benefits and risks to making AMG’s forthcoming C63 a 4-cylinder petrol-electric hybrid. Removing the emotional argument for the C63 to remain a V8, there is no question that AMG’s next C63 will be incredibly potent. It is a simple equation of physics that smaller 4-cylinder engines can spin their cranks with less inertia than a similarly turbocharged V8. By that logic, the 4-cylinder C63 could have an impressive engine-speed ceiling. 

The next C63’s engine should be an evolved version of AMG 45-series M139 2.0-litre motor, which redlines at 7 000 rpm, the same as AMG’s current 4.0-litre twin-turbo V8s. Enthusiasts will be hoping for more, with AMG engineers capable of increasing the hybridised M139 powertrain to shriek well beyond 7 000 rpm. 

By downsizing the engine so dramatically (from 8 to only 4 cylinders), AMG will reduce the weight of the ICE component of the C-Class flagship. That said, the hybrid system’s motor/s and batteries will add weight, but that mass will be positioned in optimised locations to benefit the car’s overall balance. 

Without a large V8 mounted above the front axle, the 4-cylinder C63 should have more agile handling then AMG’s current version. But will that really matter?

It's hard to forget the sound of the old 6.2-litre V8. Will new engines measure up in the sound department?

For all their lofty peak power and torque outputs, the C63s are most adored for their throaty V8 soundtracks. AMG’s spent a great deal of research in exhaust materials, tube diameters and contours to ensure its cars are loud and dramatic. Customers expect it. 

All the mechanical engineering and metallurgy in the world cannot undo the discrepancy in the quality of sound produced by a V8 and a 4-cylinder engine with half its capacity. Even with the best ignition and fuel system control technology, AMG will be unable to make its 4-cylinder C63s sound even remotely as sonorous as their V8 predecessors. And that could be a significant issue.

People who buy C63s don’t really care about tenths of a second when discussing 0-100 kph times. They care about the way their cars sound when delivering full-throttle performance between sets of traffic lights, and perhaps even more so, on the overrun. 

AMG is in an unenviable position. Compared with its V8 predecessor, the 4-cylinder C63 will better in every measure of performance, yet customers may be deterred by its less evocative soundtrack. 

Big money for only 4-cylinders 

Will C-Class AMG owners mind sharing powertrains with A-Class drivers?

Sound (or lack thereof) may not the only inhibitor to the 4-cylinder 63-series' chances of success. With each iteration of its products, AMG has added enhanced technical expertise. 

When I drove the original C63 AMG back in 2008 (the 6.2-litre naturally aspirated version, at a sweltering Phakisa circuit test session), it was an awe-inspiring model, but looking back, it had a mechanically geared limited-slip rear differential and 7-speed automatic transmission. AMG’s 2020 version of the C63 has a 9-speed transmission and torque vectoring between the rear wheels. 

As the C63 grows in complexity and incorporates increasingly exotic materials, AMG will expect customers to keep paying more for the model, but in return for ostensibly less engine and drama. To price the future C63 halfway between R1- and R2 million and expect customers to happily pay for an acoustically muted driving experience powered by only 4-cylinders might be a bridge too far. 

In the realm of pure status cars, assumption matters. AMG’s engineers will deliver a 4-cylinder hybridised C63 AMG that is superior to its V8 predecessor in all metrics, but that won’t matter – with cars of this calibre, it never does. What has made the C63 so desirable is the profound noise it emits and the way that the V8 engine gently burbles at idle. 

The collector's performance car market has taught us that cylinders equal value, over time. That is the reason why many genuinely awful-to-drive Italian supercars still command premium prices: because they have temperamental 12-cylinder engines. To give you another example: Porsches are among the best investment cars you can buy. However, the flat-6 Porsche models appreciate in value over time (especially the air-cooled ones), but 4-cylinder cars from the same era trade like South African government bonds. 

The original compact performance Benz had a 4-cylinder powerplant...

Perhaps history is also evidence that things could be different for our ominous 4-cylinder C63 predictions. Mercedes-Benz’s original performance sedan was a 4-cylinder; the car in question being Stuttgart’s 190E Cosworth Evo 2. It was an extraordinarily bold venture for Mercedes-Benz, completely out of character for the company’s deeply conservative manner in the early 1990s. 

With a dogleg gearbox and engine technology from a British specialist, the 190E Cosworth Evo was everything Mercedes-Benz wasn't (at the time). The original list price was radical, yet demand easily outstripped supply. Even more telling is that despite all the 6- and 8-cylinder AMGs that followed, the 4-cylinder 190E Cosworth remains Mercedes-Benz’s most coveted 4-door car. 

The 190E Cosworth cars set a precedent for Mercedes-Benz, the motorsport-bred 4-cylinder sports sedan was a precursor to much-beloved performance models from the Three-pointed Star. Perhaps the next C63 AMG will channel some of that legacy and be more universally accepted than we assume. Either that or M156-engined C63s are about to become an excellent investment opportunity...

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