The most misleading MOT pass rates in the UK

Every year, the DVSA publishes data from tens of millions of MOT tests. Journalists rank cars by pass rate, declare the Honda Jazz the most reliable car in Britain, and move on.

The problem is that raw pass rates are misleading.

A car doing 150,000 miles and passing 82% of the time is more impressive than one doing 15,000 miles and passing 93%. The first car has endured ten times the wear. Every suspension component, every brake disc, every tyre has covered ten times the distance. Comparing the two on pass rate alone is like comparing a marathon runner to someone who jogged to the shops.

We calculated a simple metric: failures per 10,000 miles. Take the failure rate, divide by median mileage, multiply by 10,000. This gives a mileage-normalised failure rate that strips out the advantage of barely being driven.

The results rearrange the entire league table.

Cars that look good but aren't (once you adjust for mileage)

These models have strong raw pass rates. But their median mileage is low, meaning the car simply hasn't been tested by the road.

The Honda Jazz Ex i-MMD CVT is a hybrid with a 93.8% pass rate. Impressive on paper. But the median Jazz at MOT has done just 12,382 miles. At that distance, most components are barely broken in. Once you account for mileage, it drops nearly 3,000 places in the rankings.

The BMW Z4 tells a similar story. With a median of 17,429 miles, it is clearly a weekend car that spends most of its life in a garage. Its 83.4% pass rate sounds middling for a car that has barely been driven. Adjusted for mileage, it is one of the worst performers in the country among models with 5,000 or more tests.

Cars that look bad but are actually brilliant

These models sit in the bottom half of raw pass rate tables. But they cover enormous distances, and when you account for that, they rank among the best in the UK.

The London taxi: the most underrated vehicle in Britain

The London Taxis International TX4 has a 67.9% raw MOT pass rate. On any league table sorted by pass rate, it sits near the bottom. Journalists would call it unreliable.

But the median TX4 at MOT has 187,154 miles on the clock. These vehicles work for a living. They idle in traffic for hours, crawl through London at low speeds in all weather, and rack up mileage that would retire most cars twice over.

Adjusted for mileage, the TX4 manages just 0.017 failures per 10,000 miles. That puts it in the top 6% of all models tested. It climbs 4,384 places in the rankings.

The older TX models are even more remarkable. The TX II, with a median of 324,128 miles, manages 0.010 failures per 10,000 miles. It has, on average, covered the circumference of the Earth thirteen times.

The Toyota Prius: misjudged by every raw ranking

The Prius sits at 82.4% raw pass rate. Decent, but not remarkable. You would not pick it out from a standard league table.

Yet the median Prius at MOT has covered 150,347 miles. Most of these cars are former private hire vehicles and Uber drivers. They run all day, every day.

At 0.012 failures per 10,000 miles, the Prius ranks 82nd out of 4,936 models. Among cars with 5,000 or more tests, it is 9th best in the UK. That is a car that was built to do exactly what its owners ask of it, and the data proves it.

Why this matters for car buyers

If you are buying a used car, the raw MOT pass rate tells you something, but not the full story. A high pass rate on a car with low median mileage may just mean the car has not been driven enough to develop faults. A low pass rate on a high-mileage workhorse may mean the opposite.

The mileage-adjusted metric is not perfect. It does not account for age, road conditions, or maintenance habits. But it adds a dimension that raw pass rates completely ignore.

We now show mileage-adjusted failure rates on every model page on this site. If a car's adjusted ranking differs significantly from its raw ranking, we flag it. You can see this on any model page, such as the Toyota Prius, Volvo V70, or Honda Jazz.

The adjusted top 10 (5,000+ tests)

Some surprises here. The Bentley Bentayga tops the list. Not because it is driven gently (its median mileage of 54,283 miles is respectable), but because it almost never fails: 96.9% pass rate. The BMW M3, often assumed to be thrashed, manages 103,217 median miles at 90.6% and takes second place. The Toyota Prius Plus and regular Prius both appear, confirming the hybrid drivetrain's durability at extreme mileages.

Methodology

We calculated mileage-adjusted failure rates for 4,936 models with at least 200 MOT tests and a median mileage of at least 5,000 miles. The formula is:

failPer10k = (failureRate / medianMileage) x 10,000

This is a simple normalisation. It assumes a roughly linear relationship between mileage and failure probability, which is an approximation. In reality, failure rates accelerate with age and mileage, and some components degrade with time rather than distance. But as a first-order correction, it reveals patterns that raw pass rates completely hide.

All data is from the DVSA anonymised MOT test dataset, 2024 test year.

What to do about it

If your car is due for an MOT, regardless of where it sits in these rankings, the biggest factor in passing is preparation. Check your lights, tyres, and windscreen before you go. If you suspect issues, get a pre-MOT check. BookMyGarage lets you compare MOT and repair prices from garages near you.