The 722.6 five-speed automatic is serviceable but its conductor plate, valve body, and solenoids are known service items, and the C32's transmission is singled out as the car's main weak point. Owners note the auto is well matched to the engine, with AMG Speedshift in M mode meaningfully quickening shifts.
5-speed automatic: conductor plate, valve body, and the weaker C32 gearbox
Mercedes-Benz C32/C55 AMG (W203) · mechanical