A Whangarei mechanic fears changing testing rules for older vehicles will make New Zealand roads more dangerous.
The average age of vehicles on New Zealand roads is 13 years, according to the Ministry of Transport, with Northland's cars among the country's oldest.
Figures obtained by the Motor Trade Association (MTA) - the organisation that represents repair workshops and service stations - reveal "startling" regional variations, with significantly older fleets outside the three main population centres.
The average vehicle age in the Far North is 14.4 years old and Kaipara 14.5, and in Whangarei 13.4.
Owner of Onerahi garage, Phil Newman, said 75 per cent of the vehicles he dealt with were more than 12 years old - and 75 per cent of those would fail a warrant inspection.
The main problems were shock absorbers, brakes and lights.
Having older cars on the road would be dangerous if vehicles had to undergo warrant tests only once a year, Mr Newman said.
"Brakes and tyres and things like that wear out exactly the same on a new car as they do on an old car," he said.
The comments follow the Government's September announcement of a shake-up of the vehicle licensing system, which included a proposal to extend the current six-monthly warrant of fitness tests on cars more than six years old to 12 months.
AA spokesman Mark Stockdale said while older cars had fewer safety features, that did not make them less safe.
Vehicle defects were a minor contributor to vehicle crashes, he said.
"Only about 2.5 per cent of all crashes are due to some sort of a vehicle defect and only 0.4 per cent where the vehicle defect was the sole cause of the crash.
"The reality is, very few crashes are caused by older, worn vehicles."
However, "in the event of an accident, you want to be as safe as you can" and newer vehicles were generally safer in crashes.
Average car fleet age (years)
Far North: 14.4
Waimate district: 17
New Zealand: 13.03