The potent four-cylinder engine kicks out a maximum of 416bhp and 369lb ft of torque in non-electrified form in the new A45 and its related siblings. The unit has already been engineered for longitudinal mounting as well as mild-hybrid electric boosting. It’s destined to be used in not only the next C63 but also, in a less heavily tuned form, in a follow-up to today’s turbocharged 3.0-litre V6-powered C43.
The new C63 will be offered in saloon, coupé and convertible bodystyles, with the next C43 likely to be sold in those three guises as well as an estate version.
Autocar has been told the M139 engine will adopt a 48V integrated starter motor similar to that already used by the turbocharged 3.0-litre in-line six-cylinder M256 unit, which powers the CLS 53 4Matic+ and other recent new AMG models.
In the CLS 53 4Matic+, the gearbox-mounted starter motor provides an additional 22bhp and 184lb ft of electric boosting. In the next C63, however, it is set to be tuned to provide significantly more power in combination with a similar torque loading.
The new EQ Boost hybrid drivetrain is also planned to run in combination with Mercedes’ nine-speed torque-converter MCT Speedshift gearbox.
Nothing is official at this early stage, but Affalterbach insiders with knowledge of AMG’s new model plans suggest the new four-cylinder hybrid drivetrain will match the existing second-generation C63 4Matic’s V8 engine in outright power at a maximum 503bhp. This is despite a 50% reduction in swept capacity and cylinder count. With the benefit of electric boosting, it has also been conceived to deliver up to 553lb ft of torque – a 37lb ft increase on today’s C63 S 4Matic.
Details remain scarce, although the new driveline is thought to adopt a lithium ion battery of higher capacity than the 0.9kWh unit used by the CLS 53 4Matic+. It is also expected to use a more advanced energy recuperation system that harvests kinetic energy at each wheel.
One of the most significant advantages in the adoption of the new electrified driveline is a reduction in weight over the front axle of the new C63 4Matic.
At 160.5kg, the M139 four-cylinder unit weighs 48.5kg less than the M177 V8 engine used by today’s C63 4Matic. Even with the addition of the hybrid architecture, including a disc-shaped electric motor and power electronics, the overall weight of the new powerplant is claimed to undercut that of today’s unit.
Additionally, the new powerplant’s weight is concentrated lower, which aids efforts to bring about a lower centre of gravity for the new model, theoretically improving its agility and body control. Further development plans for the next C63 4Matic include a new four-wheel drive system to provide a fully variable apportioning of power front to rear. This will allow AMG to engineer the new model with rear-wheel-drive properties in certain driving modes, much as with the larger E63 sibling. AMG CEO Tobias Moers told Autocar earlier this year that all next-generation AMG models will adopt this system, moving away from pure reardriven models due to customer demand for all-wheel drive.
The decision to provide the C63 4Matic with four-cylinder power was apparently driven by Mercedes-Benz as part of rapidly escalating efforts to reduce fleet CO2 emissions while harnessing the engineering lessons pursued during the development of the Mercedes-AMG One hypercar.