Porsche is making lots of four-door noise on its Geneva show stand, hawking new Panamera variants such as the Sport Turismo shooting brake and the range-topping Turbo S E-Hybrid. Playing the role of spoiler from clear across the hall is Mercedes-AMG and its ever-expanding line of GT models. The six coupe and convertible models currently offered each take sharp aim at a particular 911 variant, and a sleek fastback hatch sedan that's coming soon is aimed squarely at the Panamera. This GT Concept suggests what such a GT 4 might look like.

Built on the Mercedes modular MRA architecture that underpins the E63, AMG's 50th birthday present to itself highlights the brand's Sensual Purity design language of muscular proportions and highly sensuous body surfacing, all of which is coated in a Hot Red paint that is said to shimmer like liquid metal. The Panamericana grille (another subtle jab at Porsche?) apes the design of the Mercedes-Benz race cars that competed in that historic race. It features black vertical ribs painted red on their sides. Contrasting the red bodywork are a clear-coated carbon-fiber splitter, side sills, and a rear diffuser, the latter sporting a single central exhaust outlet like the one on the racy AMG GT R. Side mirrors are ditched in favor of aero-slick cameras. That feature and maybe the flush door handles are concept fantasy, but we're told that the car you see here is 90 percent production-ready.

See all 25 photos

Also production-ready is the GT Concept's powertrain; under the hood, the striking concept sports AMG's 4.0-liter twin-turbo V-8 paired to a rear-mounted electric motor, and power is sent to the ground through a torque-vectoring all-wheel-drive system. Mercedes says combined output for the hybrid is nearly 800 hp and that it will do 0-62 mph in less than three seconds.

Like the Panamera that AMG is so clearly gunning for, the production version of the AMG GT 4 will have a variety of powertrains. Below the V-8-hybrid powertrain (dubbed "EQ Power +," Mercedes' new name for its electrified drivetrains) will be a handful of sporty gas variants. Look for the hottest versions to be powered by the increasingly ubiquitous 4.0-liter twin-turbo V-8 with improved twin-scroll turbochargers nestled in the valley of the vee to further improve breathing. Base and S variants are anticipated, with outputs ranging from near 500 to over 600 hp. Lesser versions sporting an AMG-tuned riff on the M256 twin-turbo six could eventually serve as rivals for the entry-level Panameras. AMG's Speedshift MCT transmissions will likely be standard across the line.

With AMG ramping up the celebration of its 50th anniversary, you can expect to see the production Mercedes-AMG GT 4 next year, soon after the reveal of its new Formula 1-inspired hypercar.