New driving laws are being introduced from today and police say officers will be out in force ensuring drivers are obeying them.
Lower alcohol limits, a lower speed tolerance and a tightening of rules around driving licences all come into force today.
Assistant Commissioner Road Policing Dave Cliff said there would be extra police on the roads during an emphasis on road safety during this month and next month.
"Because these are the months when the fatal and serious injuries, speed and alcohol-related crashes, hit their maximum numbers."
People could still be impaired by alcohol the morning after a heavy drinking session, because it took a while for the body to get rid of the poison, he said.
"Your judgement is still not 100 per cent, your reaction time is slower, you're more likely to carry out risky driving behaviours, you're more likely to kill someone else or yourself in a road crash."
The new legislation lowers the adult breath alcohol limit from 400mcg of alcohol per litre of breath, to 250mcg.
The blood alcohol limit will reduce from 80mg of alcohol per 100ml of blood (0.08), to 50mg (0.05).
Drivers have also been put on notice they could be pulled over for driving even 1km above the speed limit.
The discretion was for officers monitoring traffic, rather than speed cameras, which had a 4km/h speed tolerance.
"People who are travelling a few kilometres an hour over a speed limit present a really major risk to others - particularly vulnerable road users in urban environments, like cyclists, kids going to and from school and elderly residents.
"Because the harder you hit them, the more damage you do - and the difference of a few kilometres per hour at pre-breaking, makes a massive difference to how hard you hit them."
There would be more likely to be zero tolerance around places such as outside schools when children were coming and going, he said.
So far this year 247 people had died on the country's roads, up from 217 at the same time last year.
"We got the lowest road toll on record last year," Mr Cliff said.
"We're now just under the second lowest on record. We're going in the right direction, but I think we could all agree, we could do a lot better."
Employers could be prosecuted if their staff drink and drive after office functions, such as Christmas partys, an Employment lawyer says.
When new health and safety laws come into effect next year there would be a "positive duty" of managers to ensure they are aware of operational risks and hazards to do with their business, Douglas Mitchell told NewstalkZB.
"So if you're going to have consumption of alcohol at your workplace, and drinking alcohol affects your driving judgement, and if you go out and drive, have a crash and are hurt, then your employer or business could be held liable under the Health and Safety Work Act."
It was about having "good host responsibility" and having processes already in place, he said.
"So you've documented these risks and that you've made steps to ensure that your employees know about these risks and how you're addressing them."
The new lower drink drive limit was a good opportunity for employers to bring the issue to employers' attention to educate them about safe drinking in the workplace, Mr Mitchell said.