Up to four in every five cars failed their tests on the first day of compulsory national car inspections yesterday, according to preliminary figures.
Faulty brakes and sub-standard emissions emerged as among the leading reasons for failure from several of the main testing centres in the State.
Some 300 cars aged nine and older underwent the 57-point inspection in 43 testing centres yesterday, the first day of the compulsory national car test.
The failure rate varied from 85 per cent in Cork to 50 per cent in Galway and 68 per cent in the Dublin testing centre in Fonthill.
The National Car Testing Service said last night the preliminary national failure rate of 60 to 80 per cent was in keeping with its expectations.
"That's what we would have expected from our pilot tests," said NCTS's general manger, Mr Richard Hoque. "What tends to happen is that car stocks rapidly improve as the defects are corrected and the failure rate goes down gradually."
He predicted the failure rate would drop next year when cars aged between eight and four become eligible for testing under the phased-in scheme.
The NCTS says it will test 1,000 cars a day this year, once it is operating at full capacity in a month. This will allow it to test the estimated 450,000 cars in the State first registered before 1992.
At the NCTS's Fonthill centre in Dublin, two cars were declared dangerous due to brakes which showed below 15 per cent efficiency. Their owners were told the vehicles should be towed away, but they chose to drive them away, according to a staff member. The NCTS has no enforcement powers against cars which it deems dangerous.
At the Cork centre, which tested 20 cars, only 15 per cent passed. The centre's manager said the reasons for failure were mostly minor, with emissions emerging as the main problem.
Half of the eight cars tested in Galway passed, with poor brakes and faulty emissions top of the failure list. In Limerick, two out of 10 tested cars passed, with poor brakes accounting for most of the failures.
Some centre managers said many of the failed cars would have passed had a pre-test service been carried out.
Mr Hoque said it was difficult to draw conclusions from the preliminary results of the first day's sample. The NCTS is due to release a more detailed breakdown of the test results today.
Mr Hoque said customers yesterday were generally happy to accept the test results and he defended the £35 charge for the test as good value for money.