M157

Based on the Mercedes M278 architecture rather than the in-house M156 it replaced, the M157 stretched bore and stroke to 98 × 90.5 mm for 5,461 cc, added a forged crank and conrods, and nestled a pair of Honeywell turbos in the V with a charge-air cooler on top. Direct injection and continuous cam phasing on both banks kept the combustion clean enough for a new decade. Debuting around 2011 in the CL 63 and S 63, it badged every car “63” despite the smaller displacement — marketing continuity over literal liters.

Outputs started near 537 PS and 800 N·m, with Performance Package and later S models pushing toward 585 PS and 900 N·m. The R231 SL 63 AMG carried it from 2012 to 2014; by the late 2010s the modular 4.0-liter M177 had taken over Affalterbach’s V8 duties.