A Government plan to get drivers into greener cars could end up taxing bigger vehicles significantly more than advertised, the National Party says.
It's the latest claim in a barrage of attacks and a social media blitz by the Opposition against the policy proposal announced last week.
Associate Transport Minister Julie Anne Genter has again disputed the numbers and accused National of "desperately lashing out".
The Government has put forward a law change that would mean lower-emitting vehicles, especially electric cars, would be discounted by up to $8000, while gas guzzlers would be hit with price increases of up to $3000 from 2021.
National now says a second part of the policy - which aims to change what cars are being brought into the country by setting emissions targets for importers - could mean heavy-emitting vehicles would be charged even more down the line.
Under that importing policy, suppliers would be have to meet certain average emissions targets across the entire fleets they import, rather than individual vehicles, or face penalties.
Opposition Leader Simon Bridges says that means while a 2019 Toyota Hilux, for example, was subject to a $1200 penalty under the "feebate" scheme, it could effectively also incur another $4650 charge for some importers once the import rules tightened up in 2025.
Those kind of costs would be passed onto consumers, he said.
But the claim assumes importers won't be offsetting gas guzzlers by importing green cars, and that the shape of the fleet being brought into the country won't change in comings years to respond to the policy.
Importers who bring in cleaner cars could incur no penalties under the policy, despite also importing heavier vehicles, a spokesman for Genter's office said, describing Bridges' claim as untrue.
"They can import vehicles with emissions that are over their fleet target, as long as these vehicles are balanced with a sufficient number of vehicles that are under the fleet target," he said.
"What, then, are car dealers in Feilding, Greymouth and Dargaville supposed to do? They can't just start selling cars their customers don't want," Bridges said in his statement.
His attack on Friday was framed as joke "apology" to Genter, for having missed the additional costs.
Genter said climate change was "no laughing matter".
The policy would save families $6800 in petrol over the lifetime of their vehicle by prompting people into greener vehicles, she said.
"The truth is that these are modest, practical policies that will result in a wide variety of cleaner cars, utes and vans being available and affordable for average Kiwi families and businesses," she said.
"Our policies have been welcomed by experts, business leaders, and even Toyota and other vehicle importers are also supportive of taking action."
She also attacked National's credentials on climate change, saying the party could not be trusted to address the issue.
"New Zealanders want to do the right thing. They care about protecting our environment and doing their bit in the global effort to stop the climate crisis."
Earlier this week, National argued the policy would also discount smaller vehicles with lower safety ratings.
Genter denies the claim.
The Opposition Party has also taken to social media, putting up more than 10 posts about what they call a "car tax", in a strategy that's drawn comparison the attack ads of Australia's Liberal Party against Labor during this year's election.
National has been aiming at tradies, farmers and families who may need bigger cars and argued they'll be subsidising people who can afford electrics.
Genter this week personally took to Twitter and Facebook to reply to criticisms of the policy and has accused the Opposition of scaremongering.
She said the charges on vehicles were small in relation to other business costs, that those who needed bigger cars would still be able to get them, and because the policy only affected newly imported cars it was unlikely to hit less well-off families.