Carrying the internal designation M139 and replacing the M133 used until now, the new twin-scroll turbo unit again displaces 1 991 cc, but weighs in at 160 kg and comes with dual-stage fuel injection as well as an electronically controlled wastegate actuator.
Hand-built by AMG at its plant in Affalterbach, and claimed to be the most powerful four-cylinder engine ever to go into mass production, the M139 will be offered in two outputs; the standard 285kW/480Nm for use in the A45, CLA 45 and GLA 45, and 310kW/500Nm in models that will carry the 45 S badge.
Regardless of output, the engine has been redlined at 7 200 rpm with the regular M139 offering its full 480 Nm from 4 750 rpm and the S its 500 Nm from 5 000 rpm.
Boosted to 1.9 bar or 2.1 bar in the case of the latter, the new motor will be mated to an eight-speed dual-clutch gearbox that debut on the B-Class at the Geneva Motor Show earlier this year. Like the now discontinued Ford Focus RS, the A45 will feature a Drift mode and up to six driving mode; Comfort, Sport, Sport+, Individual, Slippery and Race.
As before, drive will be routed to all four wheels via the performance tuned 4Matic+ all-wheel-drive system, although in this case, with the inclusion of two clutches instead of a differential that can send most of the mentioned power to the rear axle.
Despite having been spied on numerous occasions online in both prototype and pre-production forms, all while wearing extensive to minimal layers of disguise, the A45 is only expected to debut later this year or in 2020 with its sedan and crossover siblings following soon after.