According to Spain's motor.es, translated by BMW Blog, the current hatchback-wagon-styled 5 Series GT will become a 6 Series derivative alongside the coupe and convertible, and feature a sportier look than the somewhat frumpy-looking current car.
As these photos reveal, the s0-called 6 Series GT will be more coupe-like, with a more sweeping roofline and longer-than-ever liftback rear. A sharper rising belt-line is also clear in these images.
Above, Top and Below: BMW 5 Series/6 Series GT prototype
Motor.es has also detailed what it claims will be the 6 Series GT's engine range. No surprise, it largely mirrors that of the recently-revealed 2017 5 Series sedan.
Three diesels are reported: the 620d, 630d and M650d xDrive - the latter featuring the company's new quad-turbo diesel - along with the petrol-powered 630i, 640i and twin-turbo V8 M650i xDrive.
It's understood that the 6 Series GT will also be available with three plug-in hybrid powertrains in select markets - the 630e iPerformance, 640e iPerformance and 650e iPerformance.
Other details include the availability of several option packages, including the popular M Sport package, 'Executive Drive' air suspension, BMW's Active Integral Steering (four-wheel steering) system along with the remote parking technology that debuted with the larger 7 Series limousine.
It's expected the new 6 Series GT will be as significant an update as the latest 5 Series, bringing much more technology and a sporting focus to the relatively unloved model.
Several pre-production prototypes for the next-gen 5 Series/6 Series GT have been spied in recent months, with the final version expected to be revealed some time next year ahead of a late-2017 or early-2018 launch.
Above: Current-generation BMW 5 Series GT
If what the report claims proves to be true, the move would echo BMW's decision across other model lines to leave the odd-numbered names (1, 3, 5, 7) for core, conventional offerings while even numbers (2, 4, 6, 8) are reserved for numerous derivatives - think 2 Series Active Tourer, 2 Series/4 Series/ 6 Series coupes and 4 Series/6 Series Gran Coupes.
Stay tuned to CarAdvice for more BMW 5 Series and 6 Series updates in the coming months.