Best car in Britain?: How do you quantify car quality? Jeff Ferry decided to question the drivers. Now guess what they said

Quality is the most critical factor in a car company's success or failure. Over the past 20 years, Japanese manufacturers have taken a quarter of the US market, essentially by producing boring cars of impeccable quality. Here 'quality' does not mean more coats of paint or plusher leather seats; it means freedom from defects, and reliability - the capacity to clock up 50,000 miles without having to visit the garage except for servicing.

How can one judge the quality of a car? In the US, it is easy. Each year, a survey published by J D Power, a small consulting firm, ranks every car manufacturer and model sold in the US by quality. The survey, whose results make front-page news in American papers, defines quality by the average number of defects per car reported by new car owners in the first three months of ownership.

Last year, Japanese makes took four of the top five positions, with Toyota's Lexus LS400 the top model for the third year running. Last year the Lexus range sold a stunning 94,000 units in the US. Mercedes-Benz, once synonymous with quality, fell to eighth place (just behind Buick) in last year's J D Power, and its sales fell once again (by nearly a quarter in three years) to 62,000.

What about cars sold in Britain? Anecdotal evidence suggests that the quality of European cars has improved dramatically. For instance, a Jaguar dealer I know told me that three years ago he sold 34 new-registration cars on 1 August, and by 11 August 26 of the customers had brought the cars back for service; last August he sold more cars, but only half a dozen came back in the whole month. Two years ago his service area generated pounds 18,000- worth of business monthly; today it is down to pounds 4,000.

But there has never been an independent survey on car quality in Britain. The manufacturers will not release their data. J D Power would like to conduct a quality survey in Britain, and is negotiating with the Department of Transport to persuade it to release names and phone numbers of new car owners from the DVLC.

I organised the first such survey in Britain, for a documentary to be broadcast on Channel 4 tomorrow. It proved impossible to use a market research company for the task (most of the big ones refused, and a small, aggressive one demanded pounds 66,000 to rise to the challenge), so we decided to do the job ourselves.

We sent a dozen interviewers out to tackle drivers of J- and K-registration cars as they waited at car park queues and outside shops. When the results of the 1,000 interviews spilled out of our computer, they made fascinating reading.

The highest-quality car out of Britain's top 20 best-selling models was the Nissan Micra. The lowest quality was the Renault Clio. On our sample, the Clio scored 0.93 or 93 faults per 100 vehicles, while the Micra scored just seven faults per 100 vehicles. (The average was 47 faults per 100.) If our survey is an accurate representation of all new cars, it means that if you buy a Clio you are 13 times more likely to have a defect in the first year of ownership than if you buy a Micra.

There are a couple of caveats to our figures: first, we limited our league table to the 20 best-selling models in Britain. Even then, we had to exclude the newest cars because our sample had not owned them long enough to make a fair comparison with established models. And no survey with a sample of 1,000 can be perfect. But any manufacturer who disagrees with our results has a simple recourse: to publish its own figures.

Generally, the survey showed how high the quality of new cars is. At just under one fault per vehicle - our survey vehicles were owned for an average of 15 months - even the Clio, worst of the best-sellers, is remarkably good compared with cars a decade ago.

What we found confirmed that the Japanese manufacturers are way ahead of the others in quality. Not only did the Nissan Micra win the top spot, by a large margin; but, when the results for different models were aggregated, the top three positions were taken by Japanese manufacturers. This is not surprising to anyone who has visited a Japanese car factory. At the Nissan factory in Sunderland, quality standards - only 200 defective parts per million allowed from some suppliers - are astonishing. On a visit to a supplier for Nissan, also in the North-east, I saw that components awaiting shipment had been separated into two stacks. I was told that one was for Nissan, the other for Rolls-Royce; Nissan demanded a higher standard.

Yet the survey showed that the three highest-quality models sold in Britain are also built in Britain - and not all of them by Japanese companies. The obsession with quality, born in Japan, has passed to British manufacturers. That includes Rover and also dozens of component companies who supply Rover and Japanese factories in the UK. So continental companies, including Mercedes, Volkswagen and Saab, are increasing their purchases from British suppliers. Continental car buyers are catching on, too. Last year in Germany, where the overall new-car market fell by 16 per cent, Rover - boosted by the arrival of its 600 model - posted a stunning sales increase of 15 per cent.

Car Wars, the Renaissance of the British Car Industry, by Jeff Ferry, Channel 4, 5.15pm tomorrow.

(Photograph omitted)