Most 2019 Cooper diesels use the 1.5‑litre three‑cylinder diesel and were offered with a dual‑clutch automatic. That gearbox can feel sharp and needs its service history (fluid/mechatronics updates) checked; the diesel engine also brings DPF and EGR sensitivity if the car has mainly done short town runs. Parts are readily available through Mini/BMW dealers and independents, but labour and parts tend to cost a bit more than mainstream superminis.

• Automatic (dual‑clutch) gearbox behaviour and service history — no jerking, hesitation or warning lights; ask whether the gearbox oil/mechatronics have been serviced.
• DPF / EGR condition — check for recent long run regeneration evidence, warning lights, heavy soot in the tailpipe or a persistent loss of performance.
• Turbo response and smoke under acceleration — clean, linear pull with no blue/black smoke suggests healthy turbo and combustion.
• Underbody and suspension for corrosion or scraped lower bodywork (Minis are low-slung) and check rear seat space if you need regular rear passenger access.
• Battery and stop/start function — weak battery or faulty stop/start is common on 7‑year‑old cars and can affect economy and DPF regen behaviour.