The new Mercedes S-Class already offers a multitude of powertrain options varying from inline-sixes to the mighty V12 reserved for the extra-long version. The Benz and Maybach models will soon be joined by an AMG, which will be carrying the E-Performance branding as part of the company's lineup of electrified performance cars.

A thinly covered prototype of the S63e (name not confirmed yet) has now been spotted by our spies, revealing its plug-in hybrid nature by flaunting fuel caps on both rear fenders. It's pretty obvious we're dealing with the AMG version as there are many clues: Panamericana grille, larger air vents, lowered ride height, big brakes, and a quad exhaust flanking the rear diffuser.

Gallery: 2022 Mercedes-AMG S63e new spy photos

Good ol' duct tape is used to hold in place wires that seem to be going from inside the cabin through the rear door on the driver's side to underneath the prototype. AMG must be making some last-minute tweaks to the hybrid S63 by testing the electrified sporty limo near and at the Nürburgring. Judging by the light camouflage, the official reveal is likely happening sooner rather than later.

Rumors indicate the S63e will feature a twin-turbo V8 gasoline engine working together with an electric motor for a combined output estimated at over 700 horsepower. Some say there are plans for an even hotter S73e with roughly 800 hp to indirectly serve as an S65 successor. Both AMGs are likely going to come exclusively with all-wheel drive and an automatic transmission.

Bear in mind that another 800-hp AMG is inching closer as a new flagship version of the recently facelifted GT 4-Door Coupe will be revealed in the coming months with an electrified V8. Needless to say, the crown jewel of Affalterbach's upcoming electrified family will be the F1-engined One hypercar heading to customers later this year after long delays.

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