Visits to MoT testing centres have revealed "alarming disparities", according to What Car? magazine.
Some centres missed potentially dangerous faults with cars, the "mystery shopper" expedition by What Car? showed.
The magazine's "shoppers" visited six garages within five days with a six-year-old Vauxhall Corsa that the RAC had inspected and rated as an MoT failure.
Four of the centres did not pick up on a chipped windscreen or a broken clip on a brake pipe.
One of the centres, in south-west London, also failed to detect a problem with the car's track rod end ball joint.
What Car? editor in chief Chas Hallett said: "With so much disparity between different garages, we think the Government should scrap its plans for biannual MoT tests and focus instead on tightening up the current system to ensure motorists stay safe in their cars and on our roads."
A spokesman for the Vehicle and Operator Services Agency (VOSA) which runs the MoT system, said: "A number of your findings have caused VOSA some concern, which we will address with the garages involved."
Road Safety Minister Mike Penning said: "The MoT test plays an important role in making sure vehicles are roadworthy and MoT testers must be experienced and qualified mechanics.
"MoT garages are regularly inspected to make sure they meet the high standards expected and VOSA will be addressing the findings of this survey with the garages involved.
"But vehicle technology has come a long way since the 1960s when our MoT regime was introduced. That is why we want to look again at the MoT to check whether we still have the right balance of testing for modern vehicles. This will be a genuine consultation and we want to work with the industry and motorists to get the decision absolutely right."