Porsche is planning to expand its Cayenne SUV line-up with a uniquely styled coupé model. Design proposals for the new five-door liftback are described as already being at an advanced phase.

The Cayenne coupé, as the model has been christened in its development, will be positioned as a more sporting alternative to the regular Cayenne. It will receive a range of petrol and diesel engines, together with plug-in petrol-electric and diesel-electric hybrid powertrains, Porsche insiders have confirmed.

It is one of up to seven new SUVs set to be developed on a new version of the VW Group’s MLB platform currently being engineered by Audi.

Tentatively scheduled for introduction in 2018 as part of the third-generation Cayenne line-up, the Cayenne coupé has been conceived as a rival to the growing number of sporting, upmarket crossover-style vehicles, including the BMW X6, Mercedes-Benz MLC and Range Rover Sport.

"We have been considering launching a more sporting derivative of the Cayenne for some time now," a senior Porsche official revealed. "The problem has been the production capacity at our Leipzig factory and the strong sales of the regular Cayenne."

It is also understood that Porsche is concerned about preserving the exclusivity of its 911, Cayman and Boxster sports cars as it expands its SUV range. This will be a factor in whether the model gets the final production go-ahead, although approval does seem likely at present.

With further investment set to increase production capacity at the Leipzig plant when the third-generation Cayenne arrives in 2017, company boss Matthias Müller has brought the coupé variant of Porsche’s strongest-selling model into its new model development programme.

The coupé’s styling will be an evolution of that seen on today’s second-generation Cayenne, a facelift for which is imminent before the third-generation model arrives in 2017. Expect the Cayenne coupé to adopt an edgier look with tauter surfacing and overall styling inspired by the 918 Spyder, as our artist’s impression reveals. A sleeker roofline, narrow glasshouse and sloping rear end will help to differentiate it from the regular Cayenne SUV.

The interior will be shared with the new Cayenne, which again will be heavily influenced by the 918 Spyder hypercar.

The Cayenne coupé is set to be priced around 15 to 20 per cent higher than the current Cayenne, suggesting an entry-level price of around £50,000 for a 3.0-litre petrol V6 variant. As with the current Cayenne, an extensive model range is expected to include GTS, Turbo and Diesel variants, with the range being crowned by a twin-turbocharged petrol V8 with more than 550bhp in the Turbo S.

The chassis is set to be honed at the Nürburgring, with Porsche keen to push the Cayenne coupé’s sporting intentions. It will be lower overall and have a lower ride height than the Cayenne on which it is based, with the intention of giving the more road-focused model a lower centre of gravity.