A1 Cabs owner Sue Gregory said her fleet had not been affected by the audit, and hung up when asked whether her taxis were in working condition.
A taxi receives a green sticker and its Certificate of Fitness (COF) is revoked if it has safety issues. The taxi then has to be retested and issued a new COF.
A Green 2 sticker is issued and placed over its loading certificate and the vehicle is removed from operating in a passenger service. The Green 2 sticker can be removed by an authorised person once the issue is rectified or remedied.
The taxis can then go back into service.
NZTA regional manager for access and use, Rick Barber, said all 17 taxis were inspected for their mechanical safety and operating compliance with the Land Transport Act and the Operator Licensing Rule 2007.
He said owners or drivers also had their log books inspected for compliance with the Work Time and Log Book Rule 2007.
Mr Barber said of the 10 taxis, some were green stickered for insufficient tyre tread, worn inner steering rack, corrosion or rust, excessive engine oil, power steering oil and exhaust leaks, twisted suspensions and worn or damaged seatbelts.
Mr Barber said NZTA, with the police, had conducted several taxi inspections in May last year and during the Rugby World Cup. Information from those inspections had identified issues in Whangarei that had resulted in further fleet audits.
Mr Barber said taxis were on the road a lot more than private cars and were expected to be maintained to a higher standard. "Taxis do a lot of work and are sometimes double-shifted which means they are on the road 24 hours, seven days a week. As vehicles age, it becomes more important that these vehicles are regularly maintained for the safety of their drivers, their passengers, and for other people using the roads.
"In some cases, it was obvious to the NZTA that vehicles had not been maintained to the level expected."
In pre-Rugby World Cup checks in May, 2011, six taxis failed the Certificate of Fitness standard and were ordered off the road. Again, neither company would take responsibility. During a RWC game in September, A1 Cabs had four of its taxis grounded.