The fourth concept introduced this week at the 2018 Frankfurt Auto Show is the revived 8 Series Coupe.
The BMW Concept 8 Series previews the production luxury coupe which goes on sale this year.
BMW uses the 8 Series as a vision of a sports car combining uncompromising dynamic performance with modern luxury. 
The study continues the successful tradition of large coupes from BMW and interprets classic design attributes in a new language of form.
In contrast to the squarish proportions of its predecessor, the new 8 Series Concept features lines that flow like water over its Barcelona Gray Liquid body.
Creases along the hood and large side air intakes give the concept a fluid look. Bold arches framing 21-inch alloy wheels hint at the car’s rear-wheel-drive athleticism.**
At the front, we can see that the kidney grilles are actually made of one grille surround, which is a BMW first.
At the rear end, we get a close look at the taillights, which have some genuinely interesting geometry to them, as they stick out and create interesting shapes.
From the back, the Concept 8 Series looks particularly unique from other BMW's.
One can easily sport the wide, horizontal taillights with L-shaped OLED elements, along with rear spoiler molded into the trunklid and trapezoidal exhaust tailpipes.
A dark carbon-fiber diffuser can be found in the lower section of the rear apron.**
Powertrain options remain unknown at this point, but the coupe could borrow engines from the 7 Series, including a 3.0-liter turbo-six, a 4.4-liter twin-turbo V-8, and even a 6.6-liter twin-turbo V-12.
The M8 was already previewed by BMW.
SOURCE (http://www.bmwblog.com/2017/09/12/2017-frankfurt-auto-show-bmw-concept-8-series/)