How it works

The data

The figures come from DVSA's anonymised MOT tests and results for 2025, published as open data at https://open.data.dvsa.gov.uk/mot-anonymised/index.html. They cover Ford, Volkswagen and Vauxhall: 10,256,004 tests in 2025.

Contains public sector information licensed under the Open Government Licence v3.0 (https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/).

What counts as a test

Class 4 vehicles only: cars, small vans and passenger vehicles with up to eight passenger seats.

Initial tests only, the way DVSA counts failure rates: a normal test (not a retest) that ended in a pass, a fail, or a pass after rectification at the station (PRS). A PRS counts as a failure, because the car failed before it was fixed. Retests are left out, so a car is not counted twice for the same test.

How a figure is worked out

A failure rate is the share of matching tests that failed. The calculator looks for the closest match it can, then widens the search one step at a time until there are at least 100 tests:

1. model, fuel type, engine size, age and mileage
2. model, fuel type, age and mileage
3. model, age and mileage
4. model and mileage
5. model and age

Every answer says which of these it matched on and what, if anything, it gave up. The model is never dropped: a figure is always about one model.

Ages and mileages are grouped into bands. Odometer readings that cannot be right (blank, implausibly high, going backwards, or apparently in kilometres) are excluded, never corrected; those tests still count by age.

The 95% range

Each figure comes with a likely range, worked out with the Wilson score interval. The true rate for cars like this is very likely inside it. A large group gives a narrow range; a small one gives a wide range, and the page shows it either way.

When a car is compared with every car of its make at the same age and mileage, "about the same" means the comparison falls inside the car's own range: the difference could be chance.

The 100-test minimum

No percentage is shown for fewer than 100 tests. Below that, a rate moves more with luck than with the car, so the page says "Not enough data" and shows what it searched instead.

A failure item is listed only when at least 20 tests in the group failed on it, so the checklist is not built on a handful of cases.

How the data is checked

The build reproduces DVSA's own published statistics (table MOT01) from the raw data before anything else is made from it. The check is of the national class 4 initial pass rate, across every make together, not of each make separately.

Verified against DVSA's published figures for January to June 2025, where our national pass rate differs by −0.0016 percentage points. July to December 2025 has no published comparator yet.

Figures for months with no published comparator are shown, but are not described as checked until DVSA publishes the matching statistics and the check is run again.

Independent of DVSA

motrisk is independent. It is not affiliated with, or endorsed by, the Driver and Vehicle Standards Agency (DVSA).

Every figure describes what happened to comparable cars in 2025. None of it is a prediction about, or an inspection of, one particular vehicle.