What’s the most reliable car in Ireland?

More cars than ever are failing the National Car Test. A total of 48 per cent of cars – or just over 650,000 – passed the test last year compared to about 52 per cent in the years before the economic crash. Of those who failed last year, just over 4,500 were deemed dangerously unroadworthy.

Factors such as the aging national fleet and a rule introduced a few years ago which requires all cars over 10 years’ old to be tested yearly appear to be behind the higher failure rates.

What’s harder to explain are the variations in pass and failure rates for the 46 test centres around the country.

Which NCT centre has the highest pass-rate? Pass/failure rates per test centre

There's a gap of almost 30 per cent in pass and fail rates between individual test centres. While the average pass rate is 48 per cent, latest figures show a large majority of cars passed the test in Cahersiveen, Co Kerry (67 per cent), while motorists weren't as lucky in Carrick-on-Shannon, Co Leitrim (39 per cent).

The private operators of the NCT, Applus+, did not respond to numerous requests for a comment. The Road Safety Authority, however, insists luck has nothing to do with it. It points to factors such as the age of cars locally, the number of cars tested in a centre and the condition of roads as a range of potential factors.

But results for Cahersiveen – with a 67 per cent pass rate – and Clifden, Co Galway – with a 41 per cent pass rate – seem to raise more questions than answers. Neither area is known for its high-quality roads. And both test centres examined a similar number of cars.

The biggest reason for failing was an issue with the front suspension (83,833), followed by tyre condition (71,525), brake lines/hoses (65,704), stop lamps (56,715) and steering linkage (54,001).

One million-plus cars tested

We also dug down into the data to look at the performance of one million-plus cars tested in NCT centres during 2013.

When we looked at the 20 most-tested car brands, we found Toyota (51 per cent) came out tops. Renault was bottom of the pile (39 per cent).

There are all sorts of caveats to bear in mind here: some car makes are more likely to have older cars on the road or a wider variety of models.

To help level the testing pitch, we looked at the performance of the top 10 selling car models in 2009 which were due for testing in 2013.

They were: Toyota Yaris, Corolla and Avensis; Ford Focus, Mondeo and Fiesta; VW Golf and Passat; Opel Insignia; and Nissan Qashqai.

There was more good news for Toyota: the Yaris came out on top (87 per cent pass rate), followed by the Golf (86 per cent), Corolla (83 per cent), Fiesta (82 per cent) and Avensis (81 per cent).

To see how they fared over the long term, we looked at how 10-year-old versions of these models performed during the 2013 testing period.

Again, Toyota fared well. The Yaris topped the pile again (64 per cent), followed by the Corolla and Mondeo (both 63 per cent), Fiesta (57 per cent) and Focus (51 per cent).

The NCT may not be the ultimate measure of a car’s reliability. But maybe Toyota’s lofty marketing claim – “the best built cars in the world” – has some substance to it after all.