Motorists are urged to watch their speeds this summer, as the threshold will reduce to 4km/h from tomorrow until the end of January.
Police would be out in force throughout the country as part of their targeted road safety campaign, which also featured a strong focus on impaired driving and other high-risk behaviour.
Every driver stopped could expect to be breath tested, police said.
"Police want all families to have a great summer that is memorable for the good times - not a summer ruined by the grief of losing a family member to a fatal crash," Superintendent Steve Greally, the national manager of road policing, says.
December 1 marked the one-year anniversary of legislation lowering the adult alcohol limit. Supt Greally said police were encouraged that many drivers seemed to be getting the message and were choosing not to drive after drinking.
"While it is still relatively early days, what's pleasing is that as at the end of October 2015, we have seen almost 2500 fewer drivers caught in the over 400mcg/80mg bracket since the new legislation came in, compared with the same period the previous year.
"That's a really positive sign and we encourage all motorists to keep that up."
Supt Greally said police would be very happy to not issue another infringement this summer, or to have to knock on the door of loved ones to deliver tragic news.
The previous two summers marked the two lowest ever recorded number of deaths for a December/January period since records began.
From 1 December 2014 to 31 January 2015, there were 50 road deaths, compared with 42 road deaths the previous year.
By comparison, the worst December-January road toll recorded in the last 25 years was 124 deaths in 1990.
"The challenge to all of us on the roads this summer is see an even better result - but we all need to play our part to make that happens," Supt Greally said.
The road safety campaign was supported by Safer Journeys partners ACC, the New Zealand Transport Agency and the Ministry of Transport.
