Cars manufactured before 2000 were more than four times as likely to be stolen as those manufactured from 2005 onwards.
Police crime statistics show the annual number of Northland car thefts has risen over the past five years, from 586 in 2009 - a rate of 38 per 10,000 people - to 857 last year, almost 55 per 10,000 people.
Cars were most likely to be stolen in Auckland, followed by Northland, Wellington, Waikato and Christchurch.
John Himiona, manager of Metalman NZ in Whangarei, said stolen cars were coming into the scrap yard less frequently, as criminals knew they would not get them past security measures.
"We've got six cameras here. They are very visible and the police use them quite often as a tool."
Metalman did not buy anything without photo identification, which was scanned and loaded into the system.
Mr Himiona also typed every registration number into the police system to make sure the vehicle was legitimately owned. "We do as much as we can legally "
AA Insurance head of customer relations Suzanne Wolton said older cars were easier to steal.
"New Zealand has a large number of ageing, imported cars, and our claims show that older models, which have less-advanced or no security features than newer vehicles, are easy targets for thieves."
Installing an alarm and using a steering lock in full view were effective ways to deter thieves.
"Thieves will always go for the easiest, fastest option. So if you make it just a little bit harder for them, then chances are they will lose interest in your car and move on to an easier target."
One AA Insurance customer had their older model Subaru taken from their driveway and used in a robbery. Extensive damage to the ignition, as well mechanical, paint and panel damage cost more than $3300 to repair. Another was at home when burglars broke in and took the keys for her $19,000 Ford Fiesta.
They returned the next day and took the car while she was upstairs.
Nationally, police statistics show vehicle thefts have dropped from 21,629 in 2009 - or 50.1 per 10,000 people - to 19,221 last year, or 43 for every 10,000 people.