The M2 Competition switched to the S55 engine from the M3/M4, bringing much stronger pace and cooling, but also more complexity and higher running costs.
A whining rear differential or a heavy clonk when taking up drive is common on cars that have seen repeated launches or track work. Diff oil neglect and worn rear mounts make the problem worse.
The short wheelbase and stiff M chassis mean front tension struts, top mounts, and drop links take a beating on UK roads. Cars that have hit kerbs or potholes can feel nervous at motorway speed.
N55 and S55-powered cars can develop boost leaks from cracked plastic charge pipes or split boost joints, especially on mapped cars. Power drops off sharply when this happens.
Later M2 models can suffer from minor coolant loss around the expansion tank, hose joints, or auxiliary cooling hardware. It is rarely catastrophic at first, but it should not be ignored on a high-output turbo engine.