The 3.0-litre powerplant, which carries the internal codename S58, is a development of the firm’s standard B58 unit, as used in the existing 440i and other BMW models.
But as M division officials have revealed to Autocar, “it is for all intents and purposes an all-new drivetrain with significant changes to the base engine that allow it to rev beyond 7000rpm and deliver a much higher specific output” than today’s S55 engine.
As well as being earmarked for the next M4 Coupé and the first-ever M4 Gran Coupé, the new twin-turbocharged straight six is also planned to propel a new M4 Convertible, the upcoming sixth-generation M3 and, in a lesser-powered form, the second-generation M2. It will be launched in the new X3M and X4M.
An increase in power provides the new S58 engine with a higher specific output in Competition guise than the old S55 with water injection, a set-up used by the 493bhp M4 GTS.
That unit provides the outgoing M4 Coupé with 425bhp in standard guise and 444bhp in Competition form.
BMW’s M division engineers have managed to raise power by more than 11% in the standard M4 and 13% in the M4 Coupé Competition, with claimed outputs of 473bhp and 502bhp respectively.
These figures appear set to place the new model in direct competition with the 444bhp Audi RS5 and 503bhp Mercedes-Benz C63S Coupé.
Torque is also increased by 37lb ft, with the new S58 engine delivering 442lb ft on a band of revs between 2600rpm and 5600rpm.
Despite the increase in performance, the S58 engine has been developed to meet strict new emission regulations to potentially provide the standard M4 with a CO2 figure of less than 200g/km, thanks in part to the adoption of twin Otto particulate filters.