Four-door coupe shapes up in new patent submission, could be revealed before year's end

The BMW 8 Series has just been revealed in two-door coupe form, but it appears there's a four-door Gran Coupe coming soon – going by a new set of patent renderings published in overseas media this week.

A three-strong set of images was posted by website Motor1.com, said to be from the Brazilian National Institute of Industrial Property, depicting three versions of the new 8 Series: the coupe, a convertible, and four-door Gran Coupe.

It's no secret that BMW is considering a four-door version of the 8 Series, as previewed by the M8 Gran Coupe concept shown at the Geneva motor show earlier this year, though the rendering indicates it could be very close to production ready.

The styling doesn't bring many surprises, essentially adding two doors and a longer roofline to the standard two-door version.

We're guessing the 8 Series Gran Coupe will take the spot of the outgoing 6 Series Gran Coupe – which is also offered in hi-po M6 guise as well – taking on current rivals like the Bentley Flying Spur, Maserati Quattroporte, Mercedes-Benz CLS and Porsche Panamera.

Should it make it to market, the four-door 8er will almost certainly borrow its powertrain line-up from the 'standard' coupe, currently limited to the 3.0-litre turbo diesel 840d and twin-turbo V8 M850i.

At launch, both versions of the two-door coupe will feature BMW's xDrive all-wheel drive system, so for the time being we can expect the 8 Series Gran Coupe to drive all four wheels as well.

In addition to the patent rendering of the Gran Coupe, the drop-top version of the 8 Series was included in the images as well.

Like the four-door, there's no real surprises in terms of the design. The convertible borrows the coupe's body and chops the metal roof in favour of a folding fabric one.

We've had a pretty good idea of what the 8 Series Convertible will look like thanks to numerous spy shots of development prototypes, but the rendering gives us a good look at what to expect nonetheless.

Like the two-door and four-door coupes, it's likely the drop-top 8 Series will launch with the aforementioned all-wheel-drive diesel and petrol models.

Key rivals for the convertible include everything from the Mercedes-Benz S-Class Cabriolet to the Aston Martin DB11 Volante.

In terms of launch timing, we're expecting the convertible to be revealed first – going by the number of prototypes that have been spotted recently – with the Gran Coupe version likely to debut sometime early next year. We could be wrong, though.

Stay tuned to CarAdvice for all the latest.