An anti-tax lobby group has launched a petition against what it's calling a "nasty revenue grab from motorists".
Police on Thursday said they would now pull over and/or fine anyone caught over the speed limit, no matter how much over they are.
"We don't have a threshold," national road policing manager Acting Supt Gini Welch told Stuff.
"We don't have anything other than the speed limit. That's what we will enforce."
Kiwi motorists have in the past usually been able to drive at up to 10km/h over the limit without worry, except at certain times when the police have enforced lowered buffers - usually 4km/h - usually at peak holiday times.
Road safety campaigner Clive Matthew-Wilson, editor of the Dog and Lemon car guide, said it wouldn't save lies because it targets normal drivers, rather than those who speed.
"That's like trying to stop bank robberies by targeting shoplifting," he told Stuff.
The Taxpayers' Union has started a petition against the change.
"Every law-abiding motorist using cruise control has crept over the limit on downhill stretches of road," said spokesperson Jordan Williams. "Now there's going to be police hidden at the bottom ready to pounce on motorists who pass at 102km/h. It's nuts."
He said announcing the change on a Friday afternoon was "particularly cynical", with many motorists planning a weekend drive probably not hearing about.
"Let's call it what is - a nasty revenue grab from motorists."
As of Saturday morning, the petition had more than 500 signatures.
Police Minister Stuart Nash has been contacted for comment.