Later 2004 hatchbacks switched many One and Cooper models to the stronger Getrag gearbox, making them notably safer buys than early cars.
Early One and Cooper models used the Midland 5-speed gearbox, which is notorious for bearing wear and sudden failure. This is the primary concern for pre-July 2004 cars before the switch to Getrag.
The electro-hydraulic pump can overheat, run continuously, and eventually fail, sometimes damaging wiring or flattening the battery.
Front wishbone rear bushes and drop links wear quickly, giving the car vague steering and frequent MOT advisories on UK roads.
R53 Cooper S models often split the plastic tank or leak from the seam, making coolant loss easy to miss until the car overheats.