OM642

Series production began in spring 2005 after roughly forty months of development. A 72° aluminum block with cast-in liners, DOHC four-valve heads, a balance shaft between the banks, and offset crankpins for even 120° firing intervals packed third-generation common-rail (piezo injectors at up to 1,600 bar) and a Garrett variable-nozzle turbo into a package short enough for the C-Class. Compression stayed at 18:1; early car outputs clustered around 165–190 kW with well over 500 N·m from low revs — and it was the first Mercedes diesel offered with 7G-Tronic.

From the C 320 CDI and E 320 CDI through ML, GL, R-Class, vans and later BlueTEC SCR applications, the OM642 spanned passenger cars, SUVs and commercial chassis into the 2020s. It also powered Chrysler, Jeep and Freightliner cousins before the modular OM656 inline-six took over Stuttgart's diesel flagship role.