How to spot a clocked car using free MOT data
Clocking is easier than ever and still common. The mileage evidence trail every UK car leaves for free, and the physical signs that back it up.
DATA · 5 min read
Why clocking is still worth someone's while
Winding back an odometer on a modern car takes a laptop, a cable and a few minutes, and the tools are sold openly because adjusting a reading is not itself illegal, only selling the car without disclosing it. The incentive is straightforward: taking 40,000 miles off a mid-range family car can add well over a thousand pounds to what someone will pay. It is common enough on cars sold privately and at the cheaper end of the trade that a mileage check should be automatic, not optional.
The free evidence trail
Every MOT test records an odometer reading, and the DVSA publishes all of them. That gives you a timestamped mileage history going back years, for free, on any UK car with an MOT. The clearest evidence is any reading lower than an earlier one, which is close to conclusive. Our free mileage check does this comparison for you and flags every drop it finds, with the dates and the size of the discrepancy.
The subtler pattern to look for
A crude clock shows as a reading going backwards. A careful one shows as a change in the rate. Look at the miles added between each test rather than the totals: a car doing 12,000 a year for four years that suddenly does 3,000 in the year before sale has either genuinely been parked up or has been adjusted. Neither is proof, but a sharp slowdown immediately before a change of keeper is the pattern worth pausing on.
What the National Mileage Register adds
MOT data only captures readings once a year, and not at all for the first three years of a car's life. The National Mileage Register collects additional readings from servicing, finance, insurance and trade sources, which fills gaps between tests and covers newer cars that have never been tested. That is licensed data and sits in a paid report. On a car under three years old it is the only mileage evidence available, which is exactly when it is worth paying for.
The physical check that confirms it
Numbers on a screen should agree with the car in front of you. A steering wheel worn smooth, shiny pedal rubbers, a driver's seat bolster collapsed on one side and a gearknob rubbed back to the plastic do not happen at 40,000 miles. Check whether the wear on the driver's side matches the passenger side, look at the condition of the seatbelt webbing, and see whether service stamps and any stickers in the door shut or under the bonnet line up with the claimed figure.
Where you stand if it is clocked
Selling a clocked car without disclosing the adjustment is an offence under the Consumer Protection from Unfair Trading Regulations, and a dealer who does it is liable. In a private sale your practical position is far weaker, which is why the check has to happen before the money moves. Run the free mileage check on the registration first, then read the full MOT history yourself for the rate change, then look at the car with those figures in mind.