The Mercedes-AMG S63 has been reborn as a plug-in hybrid (PHEV) performance saloon developing up to 791bhp.
Set for UK sale early next year, the advanced saloon runs an updated version of the twin-turbocharged 4.0-litre V8 petrol engine used by its predecessor but also adopts a rear-axle-mounted asynchronous electric motor and a 13.1kWh lithium-ion battery – a set-up similar to that of the recently introduced Mercedes-AMG GT 63 S E Performance 4-Door Coupé.
The new petrol-electric drivetrain brings an additional 214bhp over the old S63 4Matic, making the 2023 model, officially called the S63 E Performance, the most powerful series-production S-Class model to date.
Even more impressive is the increase in torque. It extends by 391lb ft to 1054lb ft. Up to now, the most powerful S-Class was the previous-generation S65, whose twin-turbocharged 6.0-litre V12 petrol engine delivered 624bhp and 737lb ft.
The added reserves aren’t without a substantial weight penalty, though. With a claimed kerb weight of 2595kg, the new S63 tips the scales a considerable 525kg above its predecessor, albeit with what Mercedes-AMG’s head of technical development, Jochen Hermann, describes as “optimised weight distribution”.
Drive is channeled through a nine-speed AMG Speedshift MCT automatic gearbox (for the ICE) and two-speed gearbox (for the motor) as well as a fully variable AMG Performance 4Matic+ four-wheel drive with torque-vectoring for the rear wheels.
This gives the flagship AMG saloon an official 0-62mph time of 3.3sec and a governed top speed of 155mph as standard or 180mph in combination with an optional AMG Driver’s Package.
Altogether, there are seven driving modes: Electric, Comfort, Battery Hold, Sport, Sport+, Slippery and Individual.
The combination of a motor and a battery gives the S63 the capability to travel short distances on electric power alone. In Electric mode, it delivers up to 188bhp and 236lb ft of torque along with official WLTP economy of 2.90 miles per kWh and a claimed electric-only range of 20.5 miles.
As a result of the electrification measures, offical fuel consumption has been more than halved. The new S63’s WLTP average of 64.2mpg beats that of the long-wheelbase S63 it replaces by 32.5mpg, despite all that added weight.
The 400V battery consists of 1200 cells and uses liquid cooling to maintain optimum operating temperate. Its energy capacity is more than double that of the battery used by the GT 63 S E Performance. It can be charged at rates of up to 3.7kW by an AC charger.
Additionally, the driver can choose between four stages of energy regeneration, the highest of which recovers kinetic electricity produced during braking and on the overrun at up to 90kW.
Mercedes-AMG has given the new S63 greater visual differentiation from other S-Class models than its predecessor.
Among the exterior styling changes made to the standard seventh-generation S-Class is a new-look front bumper and an AMG-specific Panamericana front grille with vertical louvers.
An AMG emblem has replaced the Mercedes-Benz star on the bonnet, while the rear receives traditional S63 styling touches, including a new-look bumper with an integrated diffuser and trapezoidal tailpipes. The standard wheels are 21in in diameter.
The sporting theme continues inside with an AMG Performance steering wheel, AMG graphics for the digital instruments and selected infotainment functions, AMG-embossed upholstery for the front seats and AMG-specific trim for the dashboard, among other elements.
The S63 receives a reinforced body with what Mercedes-AMG describes as an “aluminium stabiliser” under the combustion engine, as well as an additional cross-brace between the front suspension towers. It also claims that a carbonfibre-reinforced plastic compartment used to accommodate the battery within the floor of the boot also adds rigidity to the rear.
Underneath, AMG Ride Control+ suspension with air springs and variable damping control provides automatic self-levelling and an automatic lowering function at speeds above 80mph for added aerodynamic efficiency.
The S63 also receives AMG Active Ride Control stabilisation with electromechanical anti-roll bars as well as rear-axle steering of up to 2.5deg.
Mercedes-AMG is yet to confirm pricing for the S63 in the UK, but with the GT 63 S E Performance commanding a £22,530 premium over the GT 63 S, it’s expected to rise considerably over the old S63 4Matic.