Mercedes has released the first official images of its upcoming Mercedes-AMG GT four-door undergoing testing, but still covered in its covert camouflage wrapping. This elongated version of the coupe will be seen for the first time in public next month at the Geneva Motor Show, but this time without the black and white wrap.

As far as can be seen from the official images, this new model retains a number of trademark styling cues from the coupe version. The vertical-slatted grille is positively enormous, the roof is extremely low and has a distinctly rakish fastback look about it, the rear lights are almost identical to the slim horizontal units of the coupe, and there appears to be a hatch for accessing the cargo area.

There are some notable differences from the coupe though too. The grille doesn't appear to be quite as low and menacing as the two-door, and the wheel arches are not as exaggerated as they are on the coupe, which actually makes this four-door model look a bit more like a CLS than a GT.

Although it has been confirmed what will be under the bonnet of the new AMG-GT when it goes into production in September, the general consensus is that it will launch with the 604 bhp 4.0-litre twin-turbo V-8 currently found in the E63 S 4Matic. However, officials from Mercedes have said there are definite plans for hybrid drivetrains to be offered from 2019 onwards, which suggest an even higher performance version that has been spotted undergoing testing could be one of them.

The hybrid drivetrain is expected to be offered with three different battery capacities, which will therefore mean Mercedes-AMG will sell the new model with varying amounts of power and varying ranges to suit a wider variety of customer.

Autocar in the U.K. has been told that the eventual range-topping hybrid version of the car will produce the same 805 bhp and an electric-only range of around 31 miles as the GT Concept the company previewed last year.