The upcoming BMW 8 Series Gran Coupe has been spied on the back of a transporter truck this week, ahead of an anticipated reveal later this year.Wearing almost no disguise compared to earlier protoypes that have been snapped by photographers, the 8 Series Gran Coupe is very much a four-door version of the coupe and convertible variants we've already seen meaning there aren't too many surprises in terms of the looks.Obviously there's a strong resemblance to its two-door siblings at the front and rear, with the most obvious difference being the extra pair of doors and extended roofline.The vehicle shown in the images appears to be finished in a matte grey exterior paint, and is wearing a body kit and alloys that would likely be part of an M Sport or M Performance package.It's unclear at this stage whether the 8 Series Gran Coupe will offer four or five seats (or both), given the 7 Series is currently the flagship passenger vehicle. Going by rivals like the Mercedes-Benz CLS, though, it's likely both options will be available.Having the longer roof and extra doors means the 8 Series Gran Coupe should offer much better access and accommodation in the second row than its two-door siblings, though don't expect limo-like space that's what the 7 is for.The 8 Series Gran Coupe will likely have a more sporting focus compared to the 7 Series, aiming square at the likes of the Porsche Panamera.As for powertrains, the 8 Series coupe and convertible should serve as an accurate guide, meaning we should initially see an 840d xDrive six-cylinder diesel and an M850i xDrive twin-turbo V8 at launch, followed by an M8 version next year.Stay tuned to CarAdvice for all the latest, and click on the images for the full gallery.MORE: BMW 8 Series news, reviews, comparisons and videosMORE: Everything BMW

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