Mechanics at NCT centres say the number of 'dangerous' cars they're seeing is on the rise.
Almost 6,500 'perilous' vehicles had failed by November 2016.
But that is 1,000 more than were detected in all of 2015.
These cars are so potentially dangerous, owners are advised to have them towed away from the centre rather than drive.
Serious reasons for failing the NCT include bad tyres, frayed fuel hoses and structural damage.