Mercedes is moving forward with a four-door AMG GT.

Just weeks after showing its AMG GT sedan in concept form, Mercedes has begun development of the sleekly-styled four-door.

Spotted today testing in Germany, it looks as though the production model will closely follow the styling laid out by the GT concept. We can clearly see the coupe-like roofline, along with thin-style taillights from the AMG GT sports car. The large hump on the deck lid is likely just camouflage rather than some aggressive spoiler.

The front end of the prototype remains hidden, but we can see Mercedes' signature LED headlight design. Expect the overall front end treatment to closely mimic that of the AMG GT.

Although styled like the AMG GT, the GT sedan will actually ride on the same basic platform that underpins the E-Class sedan. However, Mercedes will modify the car's chassis to accommodate a longer wheelbase and wider track.

The GT sedan will be powered a gas-electric hybrid powertrain. The gas motor will take the form of a 4.0L twin-turbocharged V8 delivering about 600 horsepower. An electric motor will boost total system output to 805 horsepower. The GT sedan will usher in a new EQ Power+ nameplate that will be used on all performance hybrids moving forward.

Power will get to the ground via an all-wheel drive system. The run from 0-60 should be dispatched in less than 3 seconds. Despite that blistering performance, the GT sedan should offer a spacious interior and a roomy trunk.

An exact timeframe for launch hasn't been revealed, but the Mercedes-AMG GT sedan could bow in production form as easily as this fall's Frankfurt Motor Show.