This here is AMG’s weapon to take on the Porsche Panamera Turbo, and it has gone from concept (it was displayed at the Geneva motor show) to prototype stage remarkably in just a week. Rumoured to be called the GT 4, it’s the four-door rendition of the sportscar.

While the heavy camouflage was designed to throw off unsuspecting automotive spies, no one outwits our intrepid snapper — this is decidedly not the next-generation CLS. The side window line near the back door isn’t the same as the CLS, while the rear end is also different. Under the bonnet it will pack the now familiar 4.0-litre twin-turbo V8, developing around 500 horsepower in the entry-level models.

There are rumours that a hybrid version with a supercar-busting 700-plus horsepower will top the line-up. The current E 63 makes over 600bhp, so that is hardly a stretching goal for the engineers. 

The production version of the AMG GT 4 is expected to be launched in 2018 as a 2019 model year car.