Cost of MOT has risen

In an undercover investigation, only eight out of 36 tests were carried out correctly.

And an increasing number of garages were passing faulty cars - up by eight garages, compared to only two five years ago.

Faults ignored included a rear seat that would not latch, worn brake discs, a damaged seatbelt, and broken buckle.

Urgent review

Which? now wants the Vehicle and Operator Services Agency (Vosa) - formerly the Vehicle Inspectorate - to carry out an urgent investigation into why cars which should obviously have failed the MOT were passed.

What did the garages miss? Passenger door locked from inside: Half the garages missed this Four testers missed a rear seat back that wouldn't latch Four garages issued test certificates despite a cut and frayed seatbelt One garage missed four failure points of a broken seat-belt buckle, wrongly coloured indicator, broken coil springs and a missing exhaust mounting

Which? bought six second-hand cars between three and 10 years old, and then introduced a variety of faults to the cars.

Some of the faults added should have been serious enough to stop the car passing.

Each car was taken to six different garages, so 36 garages were visited in total.

Helen Parker, editor of Which?, said: "The results of our investigation couldn't be more clear cut - cars which should obviously have failed the MOT are getting through.

"Vosa needs to tackle the problem urgently. It must find a way to conduct more convincing research and stop incompetent mechanics from vetting the nation's cars."

Stricter MOT

Vosa has increased the cost of MOT testing to improve standards.

It is also introducing a new computer system, which will link all MOT test centres in the country.

The centres will be able to access a database which will prompt them for test items as they carry out inspections.