Why Cornwall’s cars fail their MOT more than most of Britain

That small knot in your stomach when you hand your keys over at the garage turns out to have some basis. More than a third of MOT tests in the TR postcode area last year ended in a fail at the first attempt, well above the national rate. For drivers in Cornwall, that puts the county closer to the wrong end of the national table than most people would guess.

How Cornwall compares

The figures come from an analysis of every first-attempt MOT test on cars and light vans in Great Britain in 2025, all 33.2 million of them. CarCostCheck published its MOT failure rates study on Wednesday 14 October. It used the anonymised test results the DVSA released in June.

Across Britain, 27.7% of tests failed first time. In the TR (Truro) postcode area, 34.9% of 203,226 tests failed. Once the age of the cars is taken into account, the TR rate comes out at 32.1%. That ranks it 16th worst out of 118 postcode areas.

Next door, the PL (Plymouth) area, which also covers much of east Cornwall, did slightly worse. It came 13th, with 35.3% of 339,364 tests failing, or 32.5% after the age adjustment. Exeter (EX) was 12th on 32.7% and Torquay (TQ) recorded 31.0%.

Older cars, but not the whole story

Older cars fail more often, so the study levels the field. For each area, it works out how many fails you would expect if every car failed at the national rate for its age, then compares that with what actually happened.

Cornwall’s raw figure is higher than its adjusted one, which means the cars tested here tend to be older than average. But even with age stripped out, the TR area still sits more than four points above the national rate.

There is one quirk worth knowing. The DVSA records where the test centre is, not where the car is kept, so a car tested over the border counts towards the area of the garage that tested it.

A West Country pattern

Scotland dominates the bottom of the table. Fife (KY) and Dundee (DD) share the worst rate at 38.6%, and nine of the 10 worst areas are Scottish. Outside Scotland, the highest rates were in Bristol, the South West of England and mid Wales.

The best results were all in outer London or on its edge. Sutton (SM) came top with just 20.3%. Put another way, a car tested in Fife or Dundee was 1.9 times as likely to fail as a car of the same age tested in Sutton.

The data cannot say why. CarCostCheck notes that differences between areas may also reflect roads, weather and how testers apply the rules. The figures are not adjusted for mileage or for the makes and models on the road in each area.

Which cars fail most often

At the first MOT, around a car’s third birthday, 11.8% of vehicles failed. Among car brands with at least 5,000 first MOTs, Tesla failed most often at 15.9%, followed by MG at 14.3%. Lexus (4.8%) and Honda (6.0%) failed least.

There is a caveat on Tesla. Its cars had covered 37,320 miles on average by their first MOT, against 25,917 for all cars, and more miles mean more wear on tyres, brakes and suspension.

By 10 years old the picture shifts. Dacia (43.1%) and Renault (41.5%) had the highest fail rates, while Porsche (12.1%) and Lexus (15.6%) had the lowest, against 29.3% for all cars that age. Across all vehicles, the fail rate peaks at 42.9% at 18 years old.

Fewer fails, but watch the tyres

Nationally, things are improving. The fail rate dropped from 28.3% in 2024 to 27.7% in 2025. DVSA’s published figures for January to June 2026 show it still falling, at 27.0% against 27.6% for the same months last year.

Tyres are going the other way. Between April and June 2026, 6.55% of tests found a tyre defect serious enough to fail, up from 6.23% a year earlier. Dangerous tyre defects rose from 4.42% to 4.64%. Failures for lights, suspension and brakes all fell.

Before your next MOT, or your next car

The averages tell you the odds, but a car’s own MOT record tells you far more. The advice for anyone buying second-hand:

• Look up the car’s full MOT history, which shows every test since 2005 with each fail and advisory.
• Look for patterns, such as the same item failing year after year, advisories that turn into fails, or corrosion advisories on brakes, suspension or the underside.
• Check the mileage at each test. A drop between tests, or a long gap with no MOT, needs explaining.

And remember what the test leaves out. The MOT does not check for outstanding finance, write-offs or unfixed recalls.