A concept sedan branded as the Mercedes-AMG GT4 will reportedly be unveiled at the Geneva motor show, taking place in early March, to kick off the tuner's 50th anniversary celebrations.

Sources have told Autocar that the GT4 concept has a shape that's very much like a five-door version of the Mercedes-AMG GT coupe. The GT4 concept is said to preview a new and unique model for the Mercedes-AMG sub-brand.

Despite its visual proximity to the GT coupe and convertible, the GT4 won't use that car's bespoke platform. Instead, the production GT4 will be based around the front-engine, rear-wheel drive MRA architecture that Mercedes-Benz uses for all its vehicles from the C- through to the S-Class.

Power for the GT4 reportedly comes from AMG's 4.0-litre turbocharged V8, with a 3.0-litre turbo V6 also a possibility down the track. The V8 engine may be paired with a 48V electrical system, a small electric motor, and an all-wheel drive system with drift mode.

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Above: Mercedes-AMG GT S coupe.

To help further differentiate the GT4 from the AMG variants in the regular Mercedes-Benz range, the GT4 is said to feature a unique track and wheelbase, as well as greater use of lightweight materials, including aluminium and high-strength steel.

It's thought that the production version of the GT4 will go on sale globally during 2018. In effect, it will act as a replacement of sorts for the reportedly not-to-be-renewed CLS Shooting Brake.

According to the magazine, the GT4 is being developed under the codename 'X290' and will be pitched against the Porsche Panamera, BMW 6 Series Grand Coupe and Audi A7.