Vehicle owners overcharged for their registrations because ACC didn't have up-to-date safety information will not be refunded, the government says.
More than a quarter of all New Zealand's cars will have their risk ratings changed on 1 July, because ACC didn't have the latest safety information on them when it brought in its new registration system last year.
The blunder has been revealed to be much greater than first thought. Those initially found to be affected were paid back - but ACC Minister Nikki Kaye is ruling out any more refunds.
The government introduced a new vehicle licensing system last year, which was intended to ensure that those who drove the safest cars paid the least for their regos - while those with the least safe cars paid the most.
But it immediately became apparent that flawed car safety data was being used and last year ACC gave refunds to 20,000 motorists it had overcharged.
Ms Kaye has now revealed 774,565 New Zealand cars will have their risk ratings changed at the start of next month.
ACC spokesperson Herwig Raubal told a parliamentary select committee this morning that the agency didn't have up-to-date vehicle safety information when the new system came in.
"When we first rolled the system out we didn't have information, there was no information available in New Zealand, about when safety features changed on various models," Mr Raubal said.
Ms Kaye attempted to explain the large-scale risk rating changes to Labour's ACC spokesperson, Sue Moroney.
"You can't draft policy, Sue, when you don't have the information on particular models," she said.
Ms Moroney replied: "So you made a decision to change to a risk rating model when you didn't have all the information available, as a result thousands of New Zealanders paid more in ACC motor vehicle levy registrations, will you refund them because ACC didn't have the information and got it wrong?"
The minister responded that that wasn't correct.
"There are two parts here, the first is the average motor vehicle levy has gone from $330 to $130, the second point that I have consistently made with you is we always said there would need to be refinements to the policy."
Mrs Moroney said 14 car models, including the 2004 Kia Sportage and 2005-2010 Hyundai Sonata, would jump from the riskiest car category to the safest on 1 July.
Ms Moroney estimated that would affect 41,000 vehicles and that their owners would have been collectively overcharged about $3.8 million.