We already saw a camouflaged four-door GT in an image that Mercedes released earlier this month. To recap, it has a family resemblance to the AMG GT up front, but looks more like a CLS the rest of the way around. Expect powertrains that resemble what's available in the GT two-door, as well. A very hot twin-turbocharged 4.0-liter V8 should make this a strong performer.
Remember: if there's an R version, this "sedan" could make as much as 577 horsepower. That'd be something very special indeed. We'll undoubtedly find out the rest of the details in Geneva. Stay tuned.