The same car can look reliable one way and risky the other, depending on whether you judge it by age or by miles. A workhorse fails far more than its years suggest once you count the mileage it has covered; a garage queen has barely turned a wheel yet still fails on the things that come with age.
First-time MOT failure percentage. Each model has two dots: one for a seven-year-old car of that model, one for a car of that model at around 60,000 miles. These are the biggest divergences in the fleet, where judging a car by its age and judging it by its mileage pull hardest in opposite directions. This is the same tension behind the age versus mileage toggle on every model page.