An image of the Mercedes-AMG GT four-door model has leaked onto the internet just before its official reveal at the Geneva motor show.
A picture posted on Carscoops shows the car's front and left side. Although unconfirmed by Mercedes, it appears to match the look of development cars and those preview images previously released by Mercedes.
Our sister concern Autocar UK had previously revealed that engineers from Mercedes' performance arm are working on an even harder version of the model, with sources predicting the variant will have in excess of 800hp from a hybrid V8 powertrain.
Such a model could earn the R moniker, as with the current hottest version of the two-door GT. A Black Series model may also follow, but it's not expected until after the upcoming Black Series version of the regular two-door GT arrives.
AMG's decision to start development on a hotter GT four-door even before the regular car is revealed comes as part of its new product plan to launch variants sooner into each model's life cycle. In Detroit, where AMG recently launched its new hybrid 53 range, division boss Tobias Moers told Autocar UK that AMG "never stops with engineering development", suggesting that harder versions are worked on as soon as development on the car they're based on is completed.
He added that his personal opinion was that the four-door AMG model will be more successful than the company anticipates.
Previewed by the GT concept of 2017, the AMG GT four-door models will come with a range of EQ Power-branded petrol-electric hybrid drivelines featuring differing battery capacities, outputs and electric ranges.
The new Mercedes-AMG model has been conceved as an upmarket replacement for today’s CLS 63 and a rival to the Porsche Panamera. Sales for the production model are scheduled to begin in September 2018.
The car will be launched with the same 612hp twin-turbocharged 4.0-litre petrol V8, nine-speed automatic gearbox and fully variable four-wheel drive system as the latest E63 S 4Matic, upon which it is largely based. However, Mercedes officials have said there are also concrete plans for it to be sold with hybrid drivelines from 2019 onwards - suggesting the spotted harder version could arrive as part of that line-up.
The decision to develop the car's new hybrid driveline with three differing battery capacities will allow Mercedes-AMG to offer the car with varying power outputs and ranges.
Although the finer details are still under wraps, Autocar UK has been told that the range-topping hybrid model is set to produce the same 800hp and offer a similar 50-kilometre electric range as the GT Concept (pictured above and below).
The other versions under development are said to include a base hybrid driveline with 671hp and a 30-kilometre range and a mid-range variant with 738hp and a 40-kilometre range.
Sources suggest these units' modular nature will allow them to feature in other AMG models, including the successors to the GT Coupé and Roadster.
The hybrid driveline for the production version of the GT Concept uses AMG’s twin-turbocharged 4.0-litre V8 engine, mounted longitudinally up front, in combination with an electric motor sited within the rear axle. The engine can send power to all four wheels, while the motor delivers power exclusively to the rear wheels.
AMG says the motor is networked with a combination of extremely light batteries. These have been developed in partnership with High Performance Powertrains, the British-based AMG sister company behind the 1000hp petrol-electric driveline of the upcoming Project One hypercar.
The operation of the new petrol-electric powerplant has been derived from the hybrid unit used by the Mercedes-Benz Formula 1 team, with the battery charged while the car is being driven through brake energy recuperation and the aid of the petrol engine.