The next-generation Bentley Continental GT has been spotted testing in a Bentley bodyshell for the first time.

Previous test mules were based on a modified Porsche Panamera, but the latest set of pictures show the Continental in a production body that echoes the design of the Bentley EXP 10 Speed 6 concept car. The latest test mule sports a lower front and rear, as well as shorter overhangs and a shorter wheelbase, than the model it replaces.

The Continental range will be significantly lighter than the outgoing model, boss Wolfgang Dürheimer has said, and the first third-generation Continental model to appear should be the GT coupé in 2018. It will be followed by a new GT Convertible and the Flying Spur four-door saloon.

Like the firm’s new Bentayga SUV, the Continental’s bodyshell will be a hybrid-materials structure, with assorted high-strength steels reinforcing a body made mainly from aluminium. The current car is steel-bodied.

This change will contribute to a mass-reduction effort that should drop the car’s weight substantially below the 2375kg of today’s GT. However, it will not fall below two tonnes, Dürheimer said.

The next Continental will be based on a new platform called MSB and co-developed by Bentley and Porsche. It will also be used in lengthened form for the next-generation Panamera, which explains why the test mule in earlier spy pictures used a shortened current Panamera bodyshell with an altered ride height and cooling to meet Bentley’s specifications.

Powertrains will include the all-new 600bhp W12 that’s making its debut in the Bentayga and an updated 4.0-litre petrol V8. There will also be a petrol V6 plug-in hybrid, which will use a set-up that develops 410bhp in today’s Porsche Cayenne plug-in hybrid.

It’s unlikely that Bentley will offer the new diesel V8 in the Continental. This engine is soon to appear in the Bentayga with around 400bhp, rather than the 380bhp that it develops in the Cayenne.

Speaking at the Bentayga launch, Dürheimer said his “personal goal is a sustainable, stand-alone business with an annual production volume of 20,000 units”. He envisages seven model lines, although the Bentayga-derived sports SUV and the production version of the EXP 10 Speed 6 coupé that would make up the sixth and seventh ranges have yet tobe signed off.

Talking of the advantages of Bentley being part of the new Sports and Luxury Group at Volkswagen, Dürheimer said the VW Group test drives that take place in Namibia will now be split among the new groups and involve fewer cars. More can be achieved this way, he said.

Another gain will be sharing research and development skills, as well as a supplier base suitable for high-performance and luxury models from Porsche, Bentley and Bugatti. Dürheimer added that Lamborghini’s absence from this group “makes no sense”.