The average age of a car on the road in the EU is 12 years, varying from 8 in Austria to 17 in Lithuania.

This may well increase with electric cars being more reliable, but other failures (rust, collision) won't change much.

So 99% is too high. VEH1107 shows that 22.5% of cars in the UK were 13 years or older.

[VEH1107] https://www.gov.uk/government/statistical-data-sets/vehicle-...