Mercedes-Benz’s AMG performance division is planning to unveil a uniquely styled and engineered, 600bhp-plus four-door saloon as part of its extensive 50th anniversary celebrations next year. Set to make its debut as the Vision concept at one of a series of celebratory events next year, the new twin-turbocharged 4.0-litre V8-powered four-door is expected to carry the name GT 4 when it reaches showrooms in 2019 at a likely starting price of around £120,000. The GT 4 will become AMG’s third dedicated series production model line, following on from the SLS and the existing GT. The arrival of the four-seat saloon in concept form will complement the planned unveiling of AMG’s recently announced limited-volume, F1-inspired hyper car in what is set to become a pivotal year for the brand.
Targeted at the more sporting variants of the Bentley Continental GT and Porsche Panamera, the new saloon, code named X290, is the brainchild of AMG boss Tobias Moers. Original plans for a model in the mould of the GT 4 were first aired in a series of patent applications filed by AMG in 2012. At the time, plans centred around a long-wheelbase version of the SLS featuring two gullwing doors and a pair of small, rear-hinged rear doors. More recent plans for the performance four-door model subsequently became more closely linked to the current GT. But while the latest addition to AMG’s line-up will share key styling cues and elements of its mechanical package with the company’s headlining two-door, sources say it will be based on a different platform from the bespoke aluminium structure used by the Porsche 911 rival.
The basis for the GT4 is parent company Mercedes-Benz’s modular rear architecture (MRA), as used beneath the C63, E63 and S63. It has been specially modified for the GT4, with what insiders at AMG’s Affalterbach headquarters describe as “unique” wheelbase and track width measurements. Other dedicated features include the added use of lightweight materials within the floorpan and body structure, most notably aluminium and hot-formed high-strength steel, the adoption of which is aimed at lowering the weight of the new mode I to below that of Mercedes-AMG’s existing MRA-based models in the search of greater performance potential and enhanced handling characteristics. Power for the GT 4 will come from the latest evolution of AMG’s twin-turbocharged 4.0-litre V8, already confirmed for the new E63.
Among its developments is the adoption of new twin-scroll turbochargers mounted between the cylinder banks. The new turbos are claimed to provide improved induction qualities over the more conventional units used in the existing version of the M177-designated engine.
The engine is tipped to be offered in two states of tune from the start of sales, with both standard 4Matic+ and S 4Matic+ models. In initial range-topping S 4Matic+ guise, the new four-door’s engine output is expected to top the 603bhp of the new E63 S 4Matic+. It is understood that Mercedes’ performance car division is considering coupling the engine with a newly developed integrated starter generator (ISG). The move would not only provide it with the ability to deliver short periods of added performance via a 20bhp electric motor mounted within the gearbox but also offer instantaneous start-up, with what one engineer with knowledge of the new system referred to as “seamless” stop-start qualities.
The ISG operates via a 48V electrical system, suggesting the GT 4 could also adopt a moderate-sized lithium ion battery as part of its arsenal of high-tech developments. The engine will also feature dynamic mounts designed to suppress load changes during hard cornering and be combined with the latest version of AMG’s Speed shift MCT automatic gearbox. The transmission will be coupled to the latest version of Mercedes-AMG’s4Matic four-wheel drive system, which features a fully variable apportioning of power between the front and rear wheels. It will also incorporate a so-called ‘drift’ feature that allows the driver to channel power exclusively to the rear wheels in a move aimed at promoting oversteer.
The new AMG saloon will be underpinned by a largely bespoke suspension system that is being developed to provide unique dynamic characteristics, with greater camber adjustment and wheel control than those delivered by the suspension used on other MRA-derived AMG models, along with revised steering rates. It is not yet clear whether the GT 4 will include the three-chamber Air Body Control air springs used by the latest E63. AMG is on a roll at the moment, with booming global sales.
Moers, who was made chairman in 2013, said the performance division is approaching the size that Stuttgart neighbour Porsche was in 2010 before the Macan SUV was launched. In recent years AMG sales have boomed, with sources suggesting that the recent addition of models such as the turbo 3.0-lit re V6-powered C43, E43 and GLC43 will help to push AMG volumes to well over 80,000 units this year. The AMG line-up currently supports 31 models, with a plan to expand to 48 models in the future.