Advisory Archaeology: Digging Through a Used Car's MOT Record Before You Buy

A used car can be dressed up. A valet can hide a lot, and a folder of receipts can be selective. The MOT record is harder to edit. It is free, it is online, and it is the closest thing many cars have to a diary. Before you drive across three counties to look at a car that looks perfect in the photos, spend ten minutes on the GOV.UK MOT history service. It will not tell you everything, but it will tell you more than the shiny bonnet does.

What the record actually shows

Enter the registration number and you get the test dates, the results, the mileage recorded at each test, and the defects and advisories. Since 2018, defects have been split into dangerous, major, minor and advisory categories. That wording matters. A dangerous defect means the car should not be driven. A major defect means it has failed. An advisory is a note that something is wearing or will need attention soon. It is the car telling on itself, in civil-service language.

Mileage is the first sentence of the story

Ignore the mileage on the advert for a moment. Look at the mileage at every MOT. Work out the annual average. A car that has covered 8,000 miles a year for a decade looks different from one that sat still for two years and then suddenly covered 30,000 miles in twelve months.

Gaps are not automatically bad. A car may have been off the road, SORN, or used sparingly. But a long gap followed by a suspiciously low mileage, or a mileage that goes down between tests, needs an explanation. Clocking is illegal, but the MOT record is one of the few places where inconsistency leaves a mark. Compare the MOT mileage with the service stamps and the advert. If the numbers do not line up, ask why.

Advisories are confessions

One advisory is a note. The same advisory three years running is a pattern. Look for repeated items: tyres, brake discs, brake pipes, suspension components, corrosion. A car that has been advised on the same worn tyre four years in a row has not been cherished; it has been ignored.

Pay attention to the difference between 'monitor and repair if necessary' and a defect that has moved from advisory to major. A car can pass with an advisory and still be a sensible buy, as long as you price in the work. But repeated advisories on safety items are a reason to look harder, not a reason to shrug.

Corrosion notes deserve a translator

British winters and road salt are not kind to underside metal. Read corrosion advisories carefully. 'Surface corrosion' is different from 'corroded and seriously weakened'. Areas such as sills, subframes, suspension mounts and brake pipes are not places to gamble. If the record shows corrosion advisories that get worse year on year, budget for welding or walk away.

A single mention of light surface corrosion on an older car is not automatically a deal-breaker. A sequence of corrosion notes, each one a little more serious, is a story about a car that has been living outside and not getting the attention it needs.

When the record looks too clean

An older car with no advisories every single year is possible. It might be genuinely well maintained. It might also have had a generous tester, or it might have been repaired just before each test. A fresh pass after a long list of failures is not automatically suspicious, but it is worth asking what was done and who did it.

The opposite is also true. A car with a dramatic failure one year and a clean pass the next may have been properly fixed. The MOT record is not a court transcript. It is a set of clues.

The ten-minute routine

1. Enter the registration on GOV.UK and read the full history, not just the latest pass.
2. Write down the mileage at each test and calculate the annual average.
3. Highlight every repeated advisory.
4. Circle any corrosion, brake pipe or suspension notes.
5. Compare the MOT dates and mileage with the service records.
6. Ask the seller specific questions about the repeats.
7. If the story does not add up, walk away.

What the MOT record cannot tell you

It is not a service history. It does not tell you whether the clutch is tired, the gearbox is noisy or the engine has been neglected. It does not tell you about accident damage or the quality of a repair. It is a filter, not a guarantee. Use it to decide whether the car is worth inspecting, then get a proper look underneath or a pre-purchase inspection.

A ten-minute records check will not make you a mechanic. It will make you a harder person to sell a tired car to. That is worth the effort.