One already knows the expected over 20 years. (Timing belt, battery, tracking, tyres etc.)
Then there are the fair wear and tare through its life (not in order, just from memory).
Done over 20 years of its life:
Alternator, front springs, bushes, front break pipes, gearbox mount, parts of the exaust, front wheel bearings, pedal box, welding needed to passenger sill, new window regulators I think which was last year.
(new clutch fitted but the issue turned out to be a split in the pedal box, not the clutch! Got a refund on the clutch though).
Unlucky events: !!
Lost key, boot lock stuck, wipers refusing to turn off!
Not bad over 20 years. My impression is that VW parts last. Never the same work twice in its life. I've always felt confinfident enough not to hold breakdown cover)
I learned how to get 70 miles to the gallon by changing my driving habits, which is more miles than when it stated llife. It goes from oil change to oilchange without needing a check. This is after 171,000 miles! Low tax class and low insurance too.