Moves to make the MOT test a two-year requirement rather an annual event have been dismissed by the Government.
In 2006, Advocate General for Scotland, Lord Davidson, urged ministers to reduce the frequency of the tests as part of a review of EU red tape.
But Department for Transport minister Jim Fitzpatrick said the changes could lead to a greater number of road traffic accidents, which he labelled "wholly unacceptable".
In a written parliamentary statement, he said: "Our analysis suggests that a significant number of additional road traffic accidents would be likely if MOT test frequency was reduced.
"This is primarily because the annual MOT failure rate is already high - around 35% - and, if we were to reduce test frequency, there is a very real risk that the number of unroadworthy cars would increase significantly.
"In turn, the number of road casualties would inevitably increase."
All vehicles over three-years-old are obliged to have an MOT test every year.
Lord Davidson's review recommended that new cars should first be tested when they are four-years-old, and every two years after that.
© Press Association 2008