The other end of the table: the cars most likely to fail their MOT first time, from 104,386,556 tests. At the very bottom sits the Renault MEGANE, failing first time in 31.3% of its 78,050 tests. None of these are automatically bad buys: they're cars that need harder inspection and a bigger maintenance budget, and the individual car's history matters more than the model's average.
The bottom ten, examined
1 · Citroen C4
69.9%Fails first time in 30.1% of its 254,833 tests. The usual culprit is tyres: check it before the seller starts the engine. Average use is 9,553 miles a year, so factor wear into any offer.
2 · Dacia SANDERO
71%Fails first time in 29.0% of its 231,554 tests. The usual culprit is tyres: check it before the seller starts the engine. These do modest miles (7,509 a year on average), so the failures aren't about hard lives, they're about upkeep.
3 · DS DS3
70.3%Fails first time in 29.7% of its 93,597 tests. The usual culprit is tyres: check it before the seller starts the engine. These do modest miles (7,775 a year on average), so the failures aren't about hard lives, they're about upkeep.
4 · Ford GRAND C-MAX
73.4%Fails first time in 26.6% of its 61,314 tests. The usual culprit is tyres: check it before the seller starts the engine. Average use is 9,115 miles a year, so factor wear into any offer.
5 · Nissan NAVARA
73.9%Fails first time in 26.1% of its 117,857 tests. The usual culprit is brakes: check it before the seller starts the engine. Average use is 13,418 miles a year, so factor wear into any offer.
6 · Renault CLIO
69.2%Fails first time in 30.8% of its 359,220 tests. The usual culprit is tyres: check it before the seller starts the engine. These do modest miles (7,928 a year on average), so the failures aren't about hard lives, they're about upkeep.
7 · Renault MEGANE
68.7%Fails first time in 31.3% of its 78,050 tests. The usual culprit is brakes: check it before the seller starts the engine. Average use is 10,106 miles a year, so factor wear into any offer.
8 · Vauxhall CORSA
74.1%Fails first time in 25.9% of its 1,128,846 tests. The usual culprit is tyres: check it before the seller starts the engine. These do modest miles (7,780 a year on average), so the failures aren't about hard lives, they're about upkeep.
9 · Vauxhall INSIGNIA
73.1%Fails first time in 26.9% of its 306,582 tests. The usual culprit is tyres: check it before the seller starts the engine. Average use is 12,686 miles a year, so factor wear into any offer.
10 · Vauxhall ZAFIRA
73.8%Fails first time in 26.2% of its 188,981 tests. The usual culprit is brakes: check it before the seller starts the engine. Average use is 9,276 miles a year, so factor wear into any offer.
Quick answers
What is the least reliable car in the UK?
By first-time MOT failure risk at 3 to 8 years old, the bottom of the national table is shown above. Every model listed has at least 60,000 tests behind it, and vans are excluded so the list measures cars against cars.
Should I avoid these cars completely?
Not necessarily: a low pass rate means these models arrive at test day with worn brakes, tyres and suspension more often than average. A well-maintained example with a clean MOT history can still be a sound buy, which is why checking the individual car matters more than the badge.
Why are French superminis at the bottom?
A mix of factors the data cannot fully separate: build, parts costs that discourage upkeep, and the hard, cheap lives small cars tend to live. The pattern is consistent across three years and hundreds of thousands of tests, whatever the cause.