National is appealing a ruling by the advertising watchdog its campaign against the Government's low-emissions car feebate scheme is misleading.
The Advertising Standards Authority (ASA) said the ads, which accuse the Government of implementing a $6000 "car tax", were "likely to confuse or deceive consumers" and ordered it taken down.
The ads, which ran on Facebook and Twitter, asked viewers: "What hope does an ordinary Kiwi have for getting some relief from taxes and costs if the people running the government think $6000 is a small fee?"
It was accompanied by the phrase "Labour's car tax" but showed a picture of Green Party MP Julie Anne Genter.
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The ASA board looked at the evidence, and concluded the $6000 fee would only apply to a minority of vehicles, and the cost would be borne by the supplier - not the consumer.
"The initiative appeared to encourage suppliers to choose a fleet which balanced out high- and low-carbon emission vehicles," the ASA said in its ruling.
"The complaints board said the substantiation provided by the advertiser in this case was insufficient for the level of claim made in the advertisement.
"The board noted the reference in the advertisement to the cost being directed towards 'ordinary Kiwis'. It did not consider this was an accurate reflection of the supplier penalty and therefore the advertisement was likely to mislead consumers."
In response, National argued as a political party it shouldn't have to abide by the rules exactly as they are written.
"It has been the previous view and practice of the Advertising Standards Authority that the spirit of the code is more important than any minor technical breaches.
"People have a right to express their views and this right should not be unduly or unreasonably restricted by rules."
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A spokesperson told RNZ the party would "comply with their request in the interim, but will be lodging a comprehensive appeal".
As of Friday, the ads remained online. The ASA has no statutory power to force the party to take them down.
The ASA has plans to set up a rapid-response unit to tackle misleading political ads with far more urgency next year, which is an election year.