2021 Mercedes-AMG GT 73 EQ Performance 4-door coupe Spy shot

Mercedes-AMG is preparing a new plug-in hybrid version of its GT four-door coupe.

Our spy shots show a prototype of the AMG sedan with a hidden flap in its rear mask, located just below the right tail light. The corresponding rear fenders have the usual filler caps.

The Mercedes-AMG GT Concept, which appeared in 2017 as a preview of the GT 4-door coupe, was an impressive show car with a powerful electric V8 engine under the hood. So far, no such powertrain has taken shape, but that is about to change. In fact, AMG has already teased it, meaning it will likely debut later this year.

The electrified sedan will be positioned as the range-topper in the GT 4-door coupe lineup, much like Porsche's Panamera and Cayenne have plug-in hybrids as top options. AMG will name it the GT 73 EQ Performance 4-door coupe and is expected to be called the EQ Performance, the new performance label for Mercedes-Benz's EQ sub-brand for electrified vehicles, which is also used on Mercedes-Benz's latest Formula 1 cars.

While specs are unconfirmed, the car is rumored to have a powertrain that mirrors the setup of the original GT concept, which AMG estimated at 805 hp. Specifically, AMG says it will combine a 4.0-liter twin-turbocharged V-8 engine with a powerful electric motor that can be driven independently. Currently, the GT 4-door coupe is the GT 63 S with a maximum output of 630 hp.

The GT 4-door coupe plug-in hybrid will likely weigh more than the GT 63 S, but if it comes out with something like the 805 hp of the concept car, it should outpace the GT 63 S. With that kind of output, expect the super sedan to sprint to 62 mph in under 3.0 seconds; the GT 63 S has already clocked 3.2 seconds.

The plug-in hybrid system will eventually be introduced in other high-end models in the AMG lineup, replacing the traditional V-12 option that ends in 2019.

Aspiring buyers should expect a premium price commensurate with the additional performance this powertrain will bring; the AMG GT 63 S is already on sale starting at $159,995. For such a sum, buyers could opt for the Porsche Panamera Turbo S E-Hybrid or the battery-powered Porsche Taikan Turbo S. The timing is not clear, but it is expected to be based on Mercedes' new EV-specific platform, which will debut this year with the EQS sedan.