New Mercedes-AMG S 63 E Performance is an 800PS PHEV | GRR

That’s because, the hottest member of the S-Class line-up is more than a nose ahead of its 571PS (420kW) BMW counterpart in terms of punch. Combining the plug-in hybrid turbo-charged V8 powertrain of the rather convolutedly named AMG GT 63 E Performance, the new S 63 isn’t quite as potent as the most powerful road-going Mercedes ever. But it gets close, with a combined maximum output of 802PS (590kW) and a monstrous maximum torque of 1,430Nm (1,055lb ft).

The well known AMG 4.0-litre V8 Biturbo engine feeds power to all four wheels via a nine-speed transmission. This combines with a 13.1kWh battery pack and a two-speed electric motor rated at 190PS (140kW). These are both mounted on the rear axle, though electric drive can go to the front and rear wheels. 

Unsurprisingly, this adds a fair bit of weight to the already somewhat hefty S-Class, laden with all of its luxury tech. A curb weight of 2,595kg is the end result, and the battery-motor system doesn’t even boast particularly encouraging eco-friendly figures, given Mercedes claims you’ll only be able to travel up to 20 miles on electric power alone. 

However, Mercedes freely admits that the hybrid element of the new S 63 E Performance is there primarily for power. And the numbers the newcomer puts up certainly back that claim. 0-62mph takes a claimed 3.3 seconds, while top speed is electronically muzzled to 180mph with the optional AMG Driver’s Package. 

The battery comes with a bit of Formula 1 kudos too. The new-generation lithium-ion cell takes ‘inspiration’ from the battery tech deployed by the dominant Mercedes cars of the present hybrid F1 era, with experts from the High Performance Powertrains division in Brixworth collaborating with their colleagues in Affalterbach. 

New thermal management technology, ensuring that the 1200 cells of the battery are always in their prime operating window, is the key to unlocking the hybrid system’s impressive claimed performance. And of course, power can be fed back into the cells thanks to a four-stage energy recuperation system, ranging from minimal intervention to full one-pedal driving as you’d find in an EV. 

All the new hybrid-inspired tech and features aside, it’s still a V8-powered AMG, and with it comes all the usual bells and whistles, plus some new additions. 

A range of driving modes (now including Electric and Battery Hold functions) include the Comfort setting for what Mercedes calls an ‘optimised’ emphasis on comfort and efficiency, but things ramp up through the selections to Sport+, unlocking the full arsenal of electrically assisted V8 biturbo performance available. 

Predictably, that’s not all. Diving into the Individual mode throws open all the rules for complete customisation of everything from the engine response, aggression of the nine-speed gearbox, the damping of the electronically controlled air suspension, the volume of the adaptive exhaust system and the weight of the steering. It also opens a sub-menu for the traction control system, with three settings, Basic, Advanced and Pro. 

This new S 63 E Performance is also the first in the model’s lineage to be equipped with active engine mounts – something more usually associated with cars like the latest Porsche 911 GT3. Sensors automatically adjust the rigidity to which the 4.0-litre V8  is coupled to the body, for greater stiffness or comfort, depending on how the car is being driven. 

And of course, all of the luxury trappings of the S-Class are present on the inside, along with the S-Class’s standard MBUX infotainment setup and a smattering of driver assistance features.