Could plasma tech help prolong AMG’s ‘last V8’?

Mercedes-AMG has confirmed that a 4.0-litre unit is destined to return in a revitalised C63, as a flat-plane, mild-hybrid V8. Speaking to PH at the Nardo Technical Centre earlier this week, Felix Siggemann, exec manager for comms, suggested that the motor would effectively be all-new thanks to its new configurations and the use of 48-volt electrification. Clearly, we can expect it to sound different too, and – crucially for Euro 7 regs – lower its emissions to the point of saintliness. 

“The V8 could be the last V8 we ever make, so we want to make sure it’s future-proofed to live through the evolutions of Euro 7,” he said, referring to the forthcoming emissions standard, which will come into force in November 2026, just over eight years before the bloc’s ban on new petrol and diesel car sales takes effect. “We want to make sure [the engine’s] got a long development curve. So when it launches, it won’t be much more powerful than what came before.” 

While that suggests the new motor won’t dramatically exceed the 510hp peak of the old twin-turbo V8 that powered the previous C63 – and which bowed out of production in 2022 – it ought to still feel that bit more muscular. AMG’s decision to switch to a flat-plane crankshaft was driven by the necessary introduction of mild-hybrid technology, which not only helps to cut CO2, but also offsets the natural loss of low-down muscle caused by the switch from the cross-plane layout of its predecessors. 

With the mild-hybrid 48-volt setup there to boost the lower rev torque, the new 4.0-litre motor can take advantage of the higher-revving nature of its flat-plane crank, meaning it should have a peak power output at higher revs than the old V8’s 6,250rpm. It ought to make for a more elastic delivery, with a higher-pitched tone to boot – and one that needs far less synthesised assistance than the 680hp four-cylinder hybrid C 63 S E Performance…

“The general development goal [for the new V8] is to comply with Euro 7 and have enough of a performance buffer to keep evolving it, while staying with the 4.0-litre architecture,” reckoned Siggemann. That suggests AMG expects to keep the V8 going for several life cycles after its anticipated 2026 launch – but for it to do that, the new engine will likely need additional bolstering along the way as the regulatory noose tightens. 

Among the new innovations that might assist its long-term plans is the new plasma actuator aerodynamic technology being developed by AMG to make its performance cars more slippery through the air. Never before fitted to a full-size car in a wind tunnel, let alone the road, the plasma actuators are compact devices that sit below aerodynamically important regions of bodywork, influencing airflow by ionising (i.e. electronically charging) the air and forcing the flow to change speed and direction, like an invisible fan blowing perpendicular into the wind. 

Speaking to PH at the recent AMG GT XX event, brand aerodynamic engineer Philipp Dorr noted that his team’s technology wasn’t used on AMG’s record-breaking concept car because “the effects are limited above 200kph [124mph]”. But these hidden devices and their invisible influences on airflow are particularly useful at road car speeds, meaning body shapes that prioritise practicality or aesthetics can be made more aerodynamically efficient at the touch of a button. 

“Best of all, the actuators are not massively energy demanding, with just 50 to 150 watts needed to power one metre of actuator-influenced airflow,” said Dorr, while demonstrating the effects on a model rear wing. “They allow designers to get the shape of the car they want, even if it’s not as aerodynamically efficient as it needs to be.” 

Not surprisingly, plasma actuator tech is being developed by AMG with electric cars in mind. But as the 1,000kW-capable GT XX and its five-minute charge time show, EVs might not need the full attention of aerodynamicists for much longer. Conversely, in a world where combustion-powered restrictions are likely to ramp up before the end, it may well prove that for cars like the incoming C63, such technology ends up being essential.