Mercedes-AMG has launched the most powerful iteration of the SL sports car ever - the plug-in hybrid SL 63 S E Performance. This sleek convertible is packing an astonishing 816hp (or a nice even 600kW if you prefer).
It does that by combining a 4.0-litre V8 twin-turbo petrol engine (familiar from a whole family of high-performance AMG models) with a 150kW (204hp) rear-mounted permanently excited synchronous electric motor which gets its own dedicated two-speed automatic gearbox.
1,420Nm of torque
The combined power output of 816hp is impressive enough, but then you look at the torque figure - it's 1,420Nm. Thankfully, given that figure, the SL 63 S E uses four-wheel drive; otherwise, there'd be some surge in Michelin shares. It'll accelerate from 0-100km/h in just 2.9 seconds. Top speed? 317km/h.
That electric motor is mounted more or less directly on the rear axle, which Mercedes claims improves responsiveness and allows the motor to provide rapid-response 'tip-in' torque when you need a quick burst of acceleration, such as when overtaking. If the 4MATIC+ four-wheel drive system detects that the rear wheels are slipping - and let's face it, they're going to be - then the motor's torque is re-directed to the front wheels. Mercedes actually reckons that mounting the motor at the rear also has beneficial effects on the SL 63 S E's weight distribution.
The battery that feeds the electric motor is compact, at just 6.1kWh when fully charged, but very powerful. Leaning on the hybrid experience of the Mercedes-AMG Formula One team, the battery can provide 70kW continuous power and 150kW peak power for short bursts. It's a 400-volt unit with 560 power cells, each of which is individually cooled - a major contributor to its impressive performance. As Mercedes itself says, the battery: "is designed for fast power delivery and consumption and not for the longest possible range" but on a full charge you can theoretically run the SL 63 S E on just electric power for up to 13km. It also only charges at 3.7kW so don't go expecting any super-rapid top-ups. The battery's control systems have been designed, again inspired by F1 experience, to provide: "maximum propulsion when the driver needs it - for example, to be able to accelerate powerfully out of corners or when overtaking. The electrical power can always be accessed and frequently reproduced through high recuperation performance and demand-based recharging."
Thanks to the hybrid's low-speed efficiency, the official fuel economy figure stands at 7.7 litres per 100km, and the CO2 emissions are 175g/km.
Eight driving modes
You can choose from as many as eight different driving modes: Electric, Battery Hold, Comfort, Smoothness, Sport, Sport+, Race, and Individual. You can choose those from a dedicated AMG button via the central screen or from the now-familiar knob on the steering wheel.
There's a separate sub-mode within Comfort, which is simply called Silent, and this is the one for which your neighbours will thank you - the SL 63 S E starts up by default in this mode. It's not totally silent, though, as the stereo plays "a powerful, sonorous, AMG-typical start-up sound as acoustic feedback" when the system fires up.
Because the battery is being constantly cooled, it means that the SL 63 S E's brake energy recuperation can be maximised, and you can adjust the effect that it has on the braking through four levels, the highest of which gives you a one-pedal driving mode for town. The system can return as much as 100kW to the battery under full braking, and the system acts as an engine brake when going downhill.
Needless to say, the SL 63 S E has physical, mechanical brakes too - prodigious ones. These are AMG ceramic high-performance composite brake systems, with bronze-coloured six-piston fixed calipers at the front and single-piston floating calipers at the rear. The carbon ceramic brake discs measure 420 x 40 millimetres on the front axle and 380 x 32 millimetres on the rear axle. Clean them up and they'd make impressive dinner plates...
Underneath the car, underneath the engine, in fact, is a special mobile carbon-fibre flap which is the car's active aerodynamics system. How fast and how much it moves depends on the driving mode you've selected, but it can alter its position by 40 millimetres at a speed of 80 km/h. This creates the so-called Venturi effect, which additionally sucks the car onto the road and reduces the lift on the front axle - effectively like having an adjustable ground-effect aero package.
The moving boot spoiler helps too, and at speeds above 80km/h, it'll move through five pre-set positions to find the optimal aero balance for the car.
Active Ride Control
The SL 63 S E's suspension uses AMG's Active Ride Control setup. The dampers, which are electronically controlled and adjustable, are also hydraulically interlinked, and that hydraulic link replaces traditional hefty anti-roll bars. This system allows the SL 63 S E to constantly adjust its roll stiffness, meaning it can provide a comfortable ride (a traditional SL quality) while also keeping the body utterly flat through corners (a traditional AMG quality). The system also minimises the camber effect as the wheels react to the road, which helps to up the SL's steering precision.
The SL 63 S E also gets four-wheel steering, which allows the rear wheels to steer either in the opposite direction (up to 100km/h) or in the same direction (faster than 100km/h) as the front wheels, improving manoeuvrability around town, or stability at higher speeds.
On the outside, you'll be able to tell the SL 63 S E apart from 'lesser' SLs (a very relative term, that) thanks to the model badge being picked out in red and the extra flap at the back for the electric charging socket. There are also new exhaust trims and an E Performance badge on the front wheelarches. As standard, the SL 63 S E gets 20-inch multi-spoke AMG light-alloy wheels, painted matt black with a high-sheen finish. Those are fitted with tyres measuring 265/40 R20 at the front and 295/35 R20 at the rear.
Inside, there's a 2+2 seating layout which gives the SL 63 S E a touch of practicality, and those in the front enjoy electrically adjustable AMG sports seats, which come with heating, a built-in next-level warm air vent, and a massage function.