An analysis of 24.5 million MOT records shows that the most popular fleet cars sold in 2008 have a one-in-five chance of failing their first test.

The issue has gained relevance for fleets as many replacement cycles now reach beyond the traditional three years/60,000 miles benchmark, with many vehicles undergoing their first MOT test while still on company fleets.

The data is held by VOSA, the agency responsible for MOTs via the Government’s OpenData scheme, and has been compiled by motoring and car buying advice website honestjohn.co.uk.

According to the site, VOSA has fought to keep the data secret for years, and although some information on MOT failure rates had previously been released to the BBC, this is the first time such extensive records have been published.

As well as priming fleet operators for likely failure items at a car’s first MOT test, it could also help inform procurement decisions for vehicles joining fleets several years after the models were launched, such as the current Ford Mondeo, Peugeot 308 or Mazda6.

Data is searchable by make, model and year; it lists the reasons for failure and also shows the performance of individual cars and brands in relation to average, as well as pass rates by mileage.

Most common faults concern lighting and signalling (typically bulbs), followed by tyres, windscreen chips/cracks and brakes.

Daniel Harrison, editor of honestjohn.co.uk, said: “This is information that has been kept from car owners for many years. VOSA even fought to keep it out of public view.

“Fleet operators can take this information and use it to ensure they’re not failing a MOT test on something that can be easily fixed beforehand.

“Honestjohn.co.uk’s MOT Files demonstrate many failure items are down to the owner, rather than an inherent fault with the car.”

Although not necessarily a reflection of vehicle reliability, the data tends to support broad trends in major reliability surveys with Japanese cars appearing towards the top. And while Renault is the worst-performing mainstream manufacturer over the history of the data, with records beginning in 1980, the performance of its more recent models shows a rate of improvement better than the average for all manufacturers, reflecting the work the manufacturer has done recently to address complaints about quality and reliability.

Publication of the MOT data has prompted a response from the Society of Motor Manufacturers and Traders, which said in a statement: “The way a car is looked after, particularly in its early years, plays a vital role in how it will perform in MOT tests. Maintaining a regular servicing schedule at a franchised dealer is the best way to avoid unnecessary MOT failures.

“The Department for Transport and the UK automotive industry recognise that the quality and consistency of MOT testing is an important issue to motorists and are addressing the matter by promoting OFT-approved garages, such as those subscribed to Motor Codes.”