Police have announced an unprecedented summer holiday crackdown on those who speed and drink-drivers, with the Police Commissioner saying enough is enough.
For the first time, police will enforce a threshold of 4km/h over the speed limit during all of December and January.
The lower speed tolerance, beginning on Sunday, and greater visibility of police on the roads were among new measures announced by Police Minister Anne Tolley and Commisioner Peter Marshall in Wellington an effort to save lives over summer.
Mr Marshall said on Tuesday that a stricter tolerance limit brought down the number of deaths and injuries over public holidays by 67% in 2012.
"It's worked extremely well and, really, enough's enough. I mean, which part of the speed limit do people not understand?"
During the holidays, police will begin trialling red and orange patrol cars nationwide to heighten the visibility of officers. Over the next year, 28 cars will be introduced as existing vehicles need to be replaced.
Assistant Commissioner of road policing Dave Cliff said evidence shows that if the whole population travels more slowly, the number of serious injuries and fatal crashes will drop.
"So if we can reduce speeds by, for example, four or five kilometres an hour, the potential is to pull down injuries by about twenty percent."
Mr Cliff said high visibility tactics, combined with a reduced speed threshold during Queen's Birthday Weekends in 2010 and 2011, reduced the total number of fatality/injury crashes by 25%, compared with the previous two years.
"That's an average of 30 people whose lives were saved. If, as country, we can save that many people over a few days, the question for all of us sharing the roads these holidays is how many could we save over two months?"
Police Minister Anne Tolley said a lower tolerance limit is something that could be rolled out permanently and the Government is evaluating it.
Police have received $350,000 in additional funding from ACC to advertise the measures.
Automobile Association spokesperson Dylan Thomsen said as well as the extended crackdown on speeding, there needs to be a bigger police presence in high-risk areas over summer - and not just on highways and passing lanes.
Mr Thomsen said if the change simply results in more tickets issued, it won't solve the problem of speeding.
Six people died and 353 were injured on the roads during the Christmas holiday period last year.