The regular E 63 estate isn't due to be revealed until the next Geneva motor show in March 2017, following the E 63 saloon, which is due later this year. But this mule suggests Mercedes is already hard at work developing an even more potent version.
However, an insider has said this car is unlikely to be a Black Series model, despite the claims. Our source said AMG's hottest moniker was unlikely to feature next on an estate. Instead, this mule could be something else to sit above the regular AMG models, or even just an E 63 S.
Although the true identity of the wide-arched test car is still unconfirmed, mules for the regular E 63 estate (below) have been caught on camera on multiple occasions, revealing its large brakes and alloy wheels, quad exhausts and an aggressive front end.
The regular model was last spotted near Mercedes' test centre near the Nürburgring, which reveals the possible nature of the tests being undertaken.
The E 63 will share its engine with the Mercedes-AMG GT. It's a 4.0-litre V8 that is expected to be tuned to 600bhp – a rise of 51bhp over the current E 63, and 23bhp over the E 63 S. That power figure, combined with Mercedes' reported 100kg of weight savings in the new E-Class, signposts a notable improvement over the E 63's 0-62mph time of 4.2sec.
In the Mercedes-AMG range, the E 63 now sits above the newly introduced, Audi S6-rivalling E 43, which produces 395bhp and is reported to start at more than £50,000 by officials, although an official price is yet to be confirmed. Despite its previous absence from the E-Class line-up, the E 43 isn't expected to affect sales of the E 63, with different groups of customers targeted for each car.