It seems a tad wider than the current 6 Series, but on the other hand it doesn't look as big as one would expect an 8 Series to be.

Rumor has it the next-generation BMW 6 Series Coupe will be transformed into a Porsche 911 competitor, thus suggesting the car’s size will decrease. This camouflaged prototype spotted testing on a damp public road does not seem to be small enough to take on Stuttgart’s Nine Eleven, though. But at the same time, it doesn’t look as big as a grand tourer worthy of resurrecting the “8 Series” moniker. That’s why the attached spy images are a bit of a puzzle since we could go either way.

One thing is for sure. The prototype has provisional headlights and taillights, while the body panels appear to be the final ones. When test vehicles are caught out in the open with most of the production bits, it means an official reveal is not too far away. We’re willing to wager BMW will introduce the car either by the end of 2017 or early 2018, but hopefully we won’t have to wait until then to find out the model’s identity.

Regardless of which one it is, chances are BMW has plans for a next-generation 6 Series as well as a reborn 8 Series to serve as a direct rival for the Mercedes-Benz S-Class Coupe. The new 8 Series will basically be a two-door coupe derivative of the 7 Series from where it will inherit most of the hardware.

BMW Gran Lusso Coupe concept
BMW Gran Lusso Coupe concept

As for the design, the biggest coupe from Bavaria will likely resemble the rather stunning Gran Lusso Coupe (pictured above) introduced more than three years ago at the Concorso d’Eleganza Villa d’Este. The concept had a V12 underneath its long and elegant hood, and it would make sense for the coupe-ified 7 Series to get one as well to be a veritable GT (as in grand tourer, not the oddball Gran Turismo).

So, place your bets: 6 or 8? I’d put my money on the former.

Photos: CarPix

Gallery: 2018 BMW 6 Series or 8 Series Coupe spy photos