2015 Mercedes-Benz C63 AMG may pack 480 hp

Mercedes-Benz's new-from-the-ground-up 2015 C63 AMG has reached a final stage of durability testing, with prototypes hitting public roads near company's technical center in Germany. The BMW M3-fighting four-door is will debut at the Paris motor show in September.

The new twin-turbocharged 4.0-liter V8-powered performance sedan is set for North American sale exclusively in its rear-wheel-drive-only guise. It'll be the first in a quartet of upcoming C63 AMG models introduced into the tuning company's ever-expanding lineup within the next two years. Stablemates will include a successor to today's C63 AMG wagon and C63 AMG coupe, along with an all-new C63 AMG convertible.

The new C63 AMG sedan mirrors the changes made to the latest fourth-generation C-class sedan, revealed at the Detroit auto show. It grows in length, width and height in a move that will position further up-market than its predecessor. The adoption of a new aluminum-intensive platform structure and an predominately aluminum body shell ensures the increase in size will not have a big effect on curb weight, with Mercedes-Benz claiming savings in the region of 110 pounds, compared to the steel-bodied third-generation model.

Continuing the look established on the latest E63 AMG, the new C63 AMG will be distinguished by a series exterior styling changes aimed at providing an even more muscular appearance than standard versions of the new C-class.

We got a preview of the look on standard versions of the C-class fitted with the optional AMG optic package. But the C63 AMG will go further, featuring a heavily structured front fascia with sizeable air ducts to provide more efficient engine bay cooling, AMG's latest blade grille treatment, reworked hood, heavily flared front fenders, wider sills and a deeper rear bumper that houses trapezoidal chromed tailpipes.

Power hails from Mercedes-Benz performance division's upcoming M117 engine -- the same unit earmarked for the German car maker's SLS successor, currently known by its internal “C190” codename. The twin-turbocharged 4.0-liter direct injection V8 gasoline engine is a brand-new development. It forms a crucial role in AMG's future engine strategy, sharing a modular architecture with the twin-scroll turbocharged 2.0-liter direct injection four-cylinder gasoline mill, including its 90 mm cylinder bore space and 7 mm cylinder wall thickness.

Further details remain scarce, but AMG insiders suggest the M117 may support an output between 450 and 600 hp. Since the outgoing C63 AMG's naturally aspirated 6.2-liter V8 is already good for 451 hp, its replacement is expected to up the ante to somewhere in the region of 480 hp. Forced induction, present in the C-class based performance sedan for the very first time, should also help extend its torque reserves beyond the 443 lb-ft of its predecessor.

The recently unveiled BMW M3, by comparison, packs a new turbocharged 3.0-liter inline-six gasoline engine producing 425 hp and 405 lb-ft, while the Audi RS4's naturally aspirated 4.2-liter V8 delivers 444 hp and 317 lb-ft.

Channeling drive to the rear wheels is an updated version of AMG's existing seven-speed SpeedShift automatic gearbox. It will be supported by a range of driving aids, including a three-stage electronic stability control system and optional locking differential.

Nothing is official more than six months out from the C63 AMG's planned premiere, but insiders suggest it will be easily capable of eclipsing the standing start performance of its predecessor, which boasted an official 0-62 mph time of 4.5 seconds and a limited 155 mph top speed.

The new C63 AMG eschews the air suspension that is being made available as an option on various new C-class models for the first time, receiving a heavily reworked version of its more conventional steel-sprung arrangement with unique track widths, firmer springs and dampers, altered elastokinematics and a lowered ride height.

Despite experiencing solid sales success with recent four-wheel drive models (including the E63 AMG 4Matic and S63 AMG 4Matic) in key markets such as North America, there are no known plans for a four-wheel drive C63 AMG 4Matic.

“There will be no four-wheel drive on the C63 AMG,” AMG boss Tobias Moers told Autocar at the recent Detroit auto show. “You should never say never, but for the foreseeable future, we will not offer it on the C63 AMG, either as standard or as an option.”

Expect more news as the Paris motor show approaches.

By Greg Kable