This is the Mercedes-Benz S63 AMG, a high-performance version of the new S-Class that's designed to rival the Audi S8.
The S63 AMG gets a retuned 5.5-litre twin-turbocharged V8 petrol engine, producing 577bhp and 664lb ft of torque. That's enough to take the two-tonne saloon from rest to 62mph in 4.4 seconds (or just 4.0sec if you choose the four-wheel-drive S63 AMG 4Matic edition), and on to an electronically limited top speed of 155mph.
Despite the performance, and the hot S-Class's size, the S63 manages to reduce its fuel consumption and CO2 emissions compared with the old model. The regular and long-wheelbase S63 AMGs return 27.9mpg and emit 237g/km of CO2, while the long-wheelbase, four-wheel-drive S63 4Matic manages 27.4mpg and 242g/km.
Mercedes claims this greater efficiency is the result of efforts made to lighten the car; it's said to weigh around 100kg less than the old AMG S-Class edition, thanks to lighter wheels, a lithium-ion battery and the use of composite materials in the brakes (offered as an option). Even the spare wheel recess is made in carbonfibre, saving around 4kg.
The S63 gets subtle styling modifications over the regular S-Class, including high-gloss black trim, revised side sill panels, a black rear diffuser and chromed twin exhausts. The exhausts feature active flaps that can either remain closed or open earlier to allow the car's V8 noise to be appreciated.
The cabin features AMG sports seats, a sports steering wheel, an AMG instrument cluster, Nappa leather seats and aluminium gearshift paddles.
The chassis set-up includes Curve Dynamic Assist, which can brake the inside rear wheel during cornering to improve agility. All rear-drive S63 AMGs also get Magic Body Control, which uses a stereo camera to 'read' the road ahead and pre-adjust the car's air suspension in advance of any bumps.
The S63 AMG is due on sale in UK dealerships in the autumn. No prices have been announced, but we'd expect the line-up to start at just over 100,000, rising to around 110,000 for a long-wheelbase S63 4Matic.