How to do it in two minutes
Put the reg into AutoFinder's free screening: it draws every MOT reading on a line, puts the advert's mileage against it and does the sums. If you'd rather do it by hand from the public record, here's what to look for:
- Readings should climb steadily. A drop of more than a hundred miles between tests is the warning sign; a tester can mistype a figure, so one odd reading that the next test corrects is noise, but a figure that falls and stays down is clocking.
- The advert's mileage should be at or above the last MOT reading. Adverts round down, so a few hundred under is normal; 1,500 miles or more under the last test is the thing to question.
- Readings in kilometres (some imports) need turning into miles before you compare; multiply by 0.62.
- Work out the miles a year between tests. The UK average is about 7,000. Forty thousand or more a year in a private car is unusual and worth a question; under 3,000 with lots of advisories is too.
An example
A 2015 Astra advertised at 82,000 miles whose MOT in March recorded 118,432: the car's done 36,000 miles more than the advert says, and the advert's figure sits below the readings from three years earlier. That's a walk-away unless the seller can show why the record is wrong, which is rare.
Why it's done
A car with 80,000 miles sells for more than the same car with 120,000, so a few hundred pounds of dashboard work can add a thousand or two to the price. Selling a clocked car without saying so is an offence under the Consumer Protection from Unfair Trading Regulations 2008, but the buyer still has to spot it.
What the MOT history can't do
A car under three years old hasn't had an MOT, so there's no trail; ask for the service invoices and compare the mileages on those. And the record only catches clocking between tests: a car wound back after its last MOT shows nothing until the next one, which is why AutoFinder's inspection reads the clock in person at the viewing and compares it to the last test.