These Porsche Panamera test mules are the first evidence of the firm's engineering work on VW Group’s new rear-wheel-drive MSB platform.

The MSB platform is destined to underpin the next generation of Bentley models (including the new Continental GT and Flying Spur) and future Panamera family models, including a Panamera coupé and cabriolet.

The MSB is based heavily on today’s Panamera platform, which is unique to Porsche's big five-door hatch. It’s understood that the MSB re-engineering will see more in the way of mixed materials – aluminium as well as high-strength steel – in its construction. 

It’s also thought it will adopt the same electrical architecture that’s being developed for Audi’s MLB-Evo platform, helping reduce costs and allowing, for example, the same infotainment system to be used across all VW‘s premium models.

MSB is also more flexible in sizing than today’s Panamera, as the narrower track on one of these prototypes shows. MSB is also designed to be shortened, allowing it to underpin the next Continental GT. The Panamera’s huge centre tunnel will stay: it will help ensure the drop-top MSB models are as stiff as possible.

The transmission layout – which is natively rear-wheel drive, with the engine mounted well back in the nose, behind the front wheels – will make a big difference to the driving dynamics of future Bentley models.

The MSB offers near-ideal weight distribution, unlike the nose-heavy stance of today’s Continental models, whose engines are mounted ahead of the front axle. Like today’s Panamera, MSB will offer rear-drive, all-wheel drive and hybrid propulsion.

The first MSB model is expected to be the Bentley Continental replacement due in 2016. It's expected that the second-generation Mulsanne will be based on the long-wheelbase version of the MSB platform.