M278

Announced alongside the M276 V6 and launched in the 2010 CL 500, the M278 inherited the M273’s bore spacing, aluminum block and Silitec liners, then changed everything that decided how it ran. Third-generation direct injection with piezo-actuated injectors could fire up to five times per cycle at between 120 and 200 bar; multi-spark ignition lit the plugs repeatedly through combustion; a Honeywell turbocharger sat on each bank at 0.9 bar. Against the 5.5-liter naturally aspirated engine it replaced: 435 PS and 700 N·m, on 22 per cent less fuel.

The badges stayed at 500 and 550 even as displacement fell to 4.7 liters, and the entire line slipped under the American gas-guzzler tax — a first for a Mercedes-Benz V8. It became the default eight of the decade for the S-Class, CLS, SL and GL, while AMG built the same design out to 5.5 liters as the M157 for the 63 cars and, unturbocharged, as the M152 for the SLK 55. Production ran to 2020, when the 4.0-liter M176/M177 arrived and the V8 shrank again.