The Mercedes-Benz GT AMG, the firm's new 500bhp-plus V8-powered sports car, has entered the final phase of testing. The public debut of the rear-wheel-drive coupé is planned for the Paris motor show in October.

The exclusive computer-generated rendering shown above is based on recent spy photographs of the aluminium-bodied two-seater running at the Nürburgring circuit. The new Mercedes-Benz, which goes under the codename ‘C190’, is set to go on sale in the UK next April.

The new GT will be priced to compete directly against the likes of the Aston Martin V8 Vantage and Porsche 911 Carrera S, at about £100,000 - a considerable £70,000 less than the outgoing SLS.

The GT indirectly replaces the SLS at the very top of the Mercedes-Benz line-up, where it will act as a styling and performance figurehead for the rest of the German car maker’s line-up.

The more highly positioned and highly priced SLS is being produced in a limited five-year programme that is due to end in May. The GT, meanwhile, is scheduled to be produced over a six-year period through to 2020, at which time Mercedes-Benz plans to resurrect the SLS on an all-new carbonfibre-intensive platform structure.

At launch, the GT will offer close to 520bhp, giving it a clear power advantage over both the V8 Vantage (420bhp) and 911 Carrera S (395bhp). However, there are also plans to launch a milder version with about 480bhp in 2016. Also in the pipeline, but not planned to see the light of day until 2018, is a track-focused GT Black Series model that is set to pack up to 580bhp, according to high-ranking AMG insiders.

The basis for the GT is a modified version of the SLS’s aluminium body structure. Manufactured by Magna in Graz, Austria, it has been extensively reworked for the new two-seater. Initial reports suggest that the GT has a kerb weight of about 1480kg, some 140kg less than the SLS coupé.

Mercedes-Benz’s head of design, Gorden Wagener, has closely overseen the styling of the new car. He has described the GT as being much more contemporary in appearance than the SLS, with sharper detailing, tauter surfacing treatment and a generally more structured look that will influence the styling of other future Mercedes-Benz models. “It makes the SLS look dated,” he said.

The overall proportions of the GT are very similar to those of the SLS, with a long, probing nose, a cabin set well back within the wheelbase and a stubby rear. The intention is to provide clear links with some of Mercedes-Benz’s most revered sports cars.

Dimensionally, the GT and SLS are very similar. Nothing is official, but insiders have indicated that the GT will run close to the 4640mm length, 1940mm width and 1260mm height of the SLS.