The 2020 Golf (Mk8) diesel automatic you’re looking at will almost always use VW’s DSG dual‑clutch gearbox — that gives smooth, efficient shifts but needs periodic DSG oil/filter changes. Modern TDI diesels of this age also have DPF and (on Euro6 variants) AdBlue/SCR hardware, so prioritise examples used for longer runs rather than short stop/start commuting.

• DSG gearbox service history — confirm DSG oil/filter changes (typically around every 60k km) and test for smooth, consistent up/down shifts without jerks or hesitation.
• DPF and EGR behaviour — look for recent forced regenerations, excessive smoke on startup, or recurring DPF warning lights which indicate blocked filters from short-trip use.
• AdBlue system operation and refill history (if fitted) — check for warning lights, a working fill cap/pipe and no leaks around the tank or dosing pump.
• DSG mechatronics/clutch faults — scan for gearbox error codes and verify the car doesn’t enter limp mode under acceleration.
• Rear suspension and boot area — check for sagging or worn shocks from heavy load use and inspect tyres for uneven wear that can indicate alignment or suspension issues.