59 complaints were made to NCT centres in Cavan and Monaghan since 2017.
Through the NCT complaints process, customers can lodge a complaint on seven grounds.
These include complaints about the test, claims of damage caused during the test, booking complaints, complaints about staff attitudes, test centre delays, rules and regulations and other.
Tyres, faulty lights and suspension parts were the most common fail parts at local NCT centres last year.
A number of the complaints seen by Northern Sound News under the Freedom of Information Act shows some people questioned the results or testing procedure believing their car wasn't faulty.
Of the 38 complaints in Cavan since 2017, 20 related to the test. Seven were complaints of staff attitude, with five relating to damage.
The test was the most common complaint in Monaghan, making up almost half of the 21 complaints.
Six complaints were about damage with three complaints about rules and regulations.
There was also one appeal of the refusal of an NCT Certificate in Monaghan in 2019.
It related to a worn steering linkage and corrosion on brake disks, it wasn't upheld.
Motoring Journalist with wheelsforwomen.ie Geraldine Herbert, spoke joined Aaron McElroy on The Wider View to break down the information.
These people in Monaghan town also gave their views on the system.
