Mileage Discrepancy on an MOT: Recording Error or Clocked?

What a mileage discrepancy is

Every MOT records the odometer reading on the day. From the car's third birthday onwards that gives you a yearly trail, and the trail should only ever go up by a believable amount. A mileage discrepancy is any reading that breaks that trend: a drop, a jump far beyond a plausible year's driving, or a reading that later tests contradict.

It's the industry term for “something here doesn't add up”. It is not, on its own, an accusation. Test centres enter the mileage by hand, and a mistyped digit or a transposed pair is common. The clocked car guide covers the fraud itself; this guide is about telling the two apart.

The three patterns the record can show

Line up the readings in date order. What happens after the odd reading decides what it means.

1. A recording error

One reading sits off the trend line and the readings on either side carry on as if it wasn't there.

The 2023 figure is almost certainly a typing slip — 27,400 where 84,000-odd was meant, or a digit dropped. Nobody wound the odometer back by 45,000 miles and then forward by 68,000 in a year. The readings before and after agree with each other, so the outlier is the one in the middle.

2. A drop nothing has confirmed yet

The latest reading is lower than the one before, and there is no test after it to say whether the trend will recover.

This is the pattern you most often meet when buying, because the car is for sale between tests. It might be a keying error. It might not. The record can't settle it, so the car has to: look at the odometer now, and look at the service invoices between 2023 and today. If the dashboard reads 75,000 and the invoices agree, the 2024 entry was a slip. If the dashboard reads 41,000, you have a question the seller needs to answer.

3. A drop later readings stay below

The reading falls, and every reading after it continues from the lower figure.

Here the whole trail has stepped down and stayed down. A single typing error doesn't repeat itself across three tests at three different garages. This is the pattern that points at a wound-back odometer, and it's the one that matters most for the price and for what the car has really done.

The free check's mileage timeline shows the trail and flags a discrepancy on it. The mileage check in the Full History Report — item 4 — shows either Clear or Discrepancy, and its analysis text explains which of these patterns the record shows and what to verify.

Which reading is the outlier

A common mistake is to assume the lowest number is the wrong one. It isn't necessarily. The outlier is the reading that doesn't fit the line drawn through the others.

• If four readings climb steadily and one sits far above them, the high one is the outlier — probably an extra digit or a kilometre reading typed as miles.
• If four readings climb steadily and one sits far below, the low one is the outlier.
• If the readings before a drop agree with each other and the readings after it agree with each other, but the two groups don't agree, that's not one bad entry. That's a step, and steps are what clocking looks like.

A related trap is units. Some cars, particularly imports and some older German models, have odometers in kilometres, and a tester who enters the kilometre figure as miles creates a jump of about 60 per cent for one year. The free check converts kilometre readings where the record marks them, but a mislabelled entry can still show as a discrepancy. If a single reading is roughly 1.6 times the trend, kilometres are the first thing to suspect.

How to check the real mileage yourself

The record raises the question. The car and its paperwork answer it. In order of usefulness:

1. The odometer today. Photograph it. Compare it with the latest MOT reading and the date of that test. The difference should be a believable few months of driving.
2. Service invoices. Every garage invoice carries a mileage. A run of invoices at 40,000, 52,000 and 63,000 either fits the MOT trail or it doesn't.
3. Old MOT certificates, if the seller has them. The printed certificate shows the mileage the tester entered on the day, which is the same figure that reached the record.
4. Wear. Pedal rubbers, the steering wheel, the driver's seat bolster and the gear knob wear in proportion to use. A car claiming 40,000 miles with a pedal rubber worn through has done more.
5. Tyres and brakes. Original-fit tyres on a car claiming 60,000 miles are unlikely; so is a first set of brake discs.

If you own the car and the record is wrong

A wrong reading follows the car and turns up in every future check, so it's worth fixing.

• Within 28 days of the test, the test centre that made the entry can ask for it to be corrected through the MOT testing service. Contact the garage first; it is the quickest route.
• After 28 days, the garage can no longer change it. Contact the MOT service through GOV.UK with the test number, the date and evidence of the true mileage — a photo of the odometer and a service invoice around the same date help.
• Keep the evidence. Even if a correction is refused, a dated photograph and an invoice showing the true mileage are what your buyer will ask for.

If you're the buyer and the seller says the record is wrong, ask whether they've applied for a correction. A seller who knows the reading is a slip and has the paperwork to prove it is easy to deal with. One who shrugs is leaving the question with you.