Last year MoT failure rates rose to a record 37% for cars and light vans.
Failure rates have increased by 12% over the last four years.
Key fail items were tyres, lights, brakes and suspension - which require attention irrespective of the reliability of the vehicle or an extended warranty.
The Retail Motor Industry Federation said the increase in failure rates shows how the recession has impacted spending on servicing and repairs and underlines the critical value of the annual test.
In 2008 the Department for Transport calculated that without the MOT, there would be a horrific increase in road deaths, which would cost the country over £6billion.
John Ball, the RMI MoT Chairman said: “Road deaths are at a modern time low as a result of improved car design and this country’s world class MoT system.
"Common sense would suggest with modern cars being more reliable the fail rate would be in decline – it’s the opposite – with government figures showing in 2009 the failure rate continues to grow."