MOT failure figures released by the Department for Transport earlier this year contained numerous errors, the organisation has admitted.
Contacted by Autocar after analysis showed that some of the percentage failure rates didn't tally with the published number of MOT tests and failures for some car models, a DfT spokesman admitted, "There are quite a lot of anomalies in the figures.
"These are the result, chiefly, of human error," said a spokesman. "We relied on MOT garages inputting the data manually into the system, and it's clear when you look through that not all the figures are correct."
The errors include figures for several Renault models, which came in for particular criticism following a report on the figures by the BBC.
Now the DfT has vowed to check its figures more carefully, and publish them regularly to provide consumers with reliable information.
"We plan to release the information more regularly, and in a format people will understand," said the spokesman.
In addition to admitting anomalies in the data, the DfT has published a technical note to explain how it reached its figures.
Included in these notes are explanations that the data doesn't differentiate between cars and vans in, for instance, the case of the Ford Escort. Results for some vehicles are also assimilated, for instance in the case of Vauxhalls and Opels, and Daewoos and Chevrolets.
In reaction, a Renault spokesman said: "We welcome the information being produced correctly in an easier format for people to understand."