The MOT U-Curve: why a 30-year-old car passes as often as an 11-year-old

A car that first took its MOT at three years old passes 89.3% of the time. By 18, that number has fallen to 67.6%. Most people would expect the line to keep falling. It does not. At 22, the pass rate has climbed back to 69.6%, matching a 15-year-old car. At 25, it reaches 73.0%, the same as a 12-year-old. By 30, it hits 74.9%, level with an 11-year-old.

This is not a data error. It is 57 million tests showing survivorship bias in action: the worst cars get scrapped, and what remains is a fleet of survivors that were worth keeping.

The decline everyone expects

Cars enter the MOT system at three years old. At that point, 89.3% pass first time, based on 3,362,857 tests. The decline from there is steady and predictable. By age 5, it is 87.4% (4,283,796 tests). By 10, it drops to 77.2% (4,057,114 tests). Rubber perishes. Brake discs wear. Suspension bushes deteriorate. Corrosion starts to take hold. None of this is surprising.

The decline accelerates through the teens. Age 15: 69.5% (2,353,366 tests). Age 17: 68.2% (1,964,364 tests). Age 18: 67.6% (1,499,000 tests). That is the bottom.

The turn

After age 18, the curve reverses. Not dramatically at first: age 19 is 67.8%, age 20 is 67.7%. But from 21 onwards the recovery is clear and consistent. Age 22: 69.6%. Age 25: 73.0%. Age 27: 74.6%. Age 30: 74.9%. That is a 7.3 percentage point recovery from the bottom, on a sample of 68,658 tests at age 30 alone. This is not noise. It is a pattern visible across millions of records.

Why it happens: natural selection for cars

The explanation is survivorship bias. The concept is well established in statistics: when you only observe the things that made it through a selection process, you get a skewed picture of the whole group. The classic example is World War II aircraft. The military studied bullet holes on returning bombers and planned to armour those areas, until statistician Abraham Wald pointed out that the planes that did not return were the ones hit in the areas without holes. The survivors were misleading.

Cars work the same way. At age 10, the fleet is large: 4,057,114 tests. It includes everything from garaged enthusiast cars to neglected daily drivers held together by hope and cable ties. By age 20, the fleet has shrunk to 885,580 tests. By 25, it is 262,535. By 30, just 68,658. The cars that were not worth fixing have been scrapped. What remains are the cars that someone cared enough about to maintain: the enthusiast-owned classics, the low-mileage garage queens, the mechanically sound workhorses that justified the repair bills.

Tests on cars aged 20 and over account for just 6.1% of the total fleet. That 6.1% is not a random sample of all cars ever made. It is the best of what survived.

The age 18 graveyard

Age 18 is the inflection point for a reason. At 18, a car is too old for any remaining warranty coverage, too young to be a classic, and too depreciated for most owners to invest in significant repairs. These are the neglected daily drivers: the cars bought cheap, run hard, and scrapped when the next MOT failure costs more than the vehicle is worth.

The numbers tell the story. Between age 15 and age 20, the testing pool drops from 2,353,366 to 885,580. That is 1.5 million cars disappearing from the MOT system in five years. Some are exported. Some are SORN'd. Most are scrapped. And the ones that get scrapped are disproportionately the ones that would have failed.

Which makes recover best

Not all brands experience the U-curve equally. Some makes produce cars that survive and thrive into old age. Others barely improve even after the weakest examples are culled.

Honda is the standout. Its cars recover 12.6 percentage points between age 18 and 25, climbing from 66.2% to 78.8%. That is a remarkable figure, and it reflects Honda's reputation among enthusiasts: Civic Type Rs, Accords, and CR-Vs that are kept running well past the point where lesser cars would be scrapped. The engines are bulletproof. The owners know it.

Mercedes recovers 2.3 percentage points, from 71.3% to 73.6%. These are the W211 E-Classes and W220 S-Classes that have passed into the hands of owners who understand the maintenance demands. Vauxhall, surprisingly, recovers 3.2 points. The Vauxhalls that make it to 25 are not the Corsas that rusted away at 15. They are the Cavaliers and Omegas that someone cared about.

BMW barely moves: 74.6% at 18, 75.1% at 25. BMW starts from a higher base than most, so there is less room to climb. But the flat recovery also suggests that the surviving BMWs are maintained to a consistent standard rather than an exceptional one.

Ford recovers just 0.6 points, from 64.6% to 65.2%. The survivors are not treated much better than the casualties. A 25-year-old Ford, on average, is still a car that was bought cheap and maintained on a budget.

The 40-year cliff: MOT exemption

Our data extends to age 30, but there is an important caveat for the oldest vehicles. Since May 2018, cars manufactured or first registered over 40 years ago are exempt from the MOT in the UK, provided they have not been substantially changed. This is a rolling exemption: in 2026, vehicles from 1986 and earlier qualify. The Federation of British Historic Vehicle Clubs estimates that around 1.5 million historic vehicles are on UK roads, many of which no longer appear in MOT testing data.

This means the U-curve we observe in the data is actually understated for the very oldest vehicles. The most cherished, best-maintained classics have already left the MOT system entirely. What we see at ages 25 to 30 includes only vehicles young enough to still require testing.

What this means if you are buying

The U-curve carries a practical message for used car buyers. Age alone does not determine MOT outcomes. A well-maintained 25-year-old Honda, with a pass rate of 78.8%, is a better MOT prospect than the average 15-year-old car at 69.5%. The key word is well-maintained: the U-curve is not evidence that old cars are inherently good. It is evidence that the bad ones have been removed from the data.

If you are looking at a car over 20 years old, the MOT history matters more than the age. A full history of first-time passes, consistent mileage, and no structural advisories tells you this car is one of the survivors. A history of failures, re-tests, and patchy gaps tells you it might be on borrowed time.

For older vehicles, a pre-MOT inspection through a service like BookMyGarage can identify problems before they become formal failures. Corrosion in structural areas, worn suspension components, and brake condition are the areas most likely to catch out an older car.

Frequently asked questions

What is the MOT pass rate for a 30-year-old car?

The average MOT pass rate for a 30-year-old car is 74.9%, based on 68,658 tests in the DVSA data. This is higher than cars aged 11 to 19, because the worst examples have already been scrapped by that point.

At what age do cars have the lowest MOT pass rate?

Cars aged 18 have the lowest average MOT pass rate at 67.6%, based on 1,499,000 tests. After 18, the rate begins to recover as the fleet is filtered by survivorship bias.

What is survivorship bias in cars?

Survivorship bias in cars means that older vehicles still on the road tend to be the ones that were well-maintained and worth keeping. The unreliable, rusty, or neglected ones were scrapped years ago. This makes the surviving fleet appear healthier than you would expect for its age.

Are classic cars exempt from the MOT?

Yes. Since May 2018, vehicles manufactured or first registered over 40 years ago are exempt from the MOT test in the UK, provided they have not been substantially changed. This is a rolling exemption that moves forward each year. Owners can still voluntarily submit their vehicle for an MOT.