"If you think about a continuum instead of putting on a number, we've got a really ambitious aspirational goal," she said. "The only way you can say you've met your goal is to have achieved zero deaths and injuries on our roads."
But although acknowledging that was unlikely in her lifetime, she said that at least there were 95 fewer families than last year who had suffered the grief of losing loved ones in road crashes.
"We say one death usually touches about 500 people, so that's 47,000 New Zealanders who haven't been touched by road deaths this year."
Mrs Rose believed an increasing public awareness of the need to behave safely on the roads was the police's main ally in beating down the toll. That included parents reminding their teenage children about the new zero drink-drive limit for drivers aged under 20, and "some great advertising".
The "ghost chips" television advert featuring a young man talking his intoxicated friend out of driving was particularly effective, and the police were hearing about people of all ages borrowing from its script in real life.
Such messages had seen large reductions in deaths among young people, starting with those aged 15 to 19, of whom 33 had been killed by December 23 compared with 51 by the same time last year and 52 in 2009.
The toll for those aged 20 to 24 stood at 44, against 61 last year, and was just 45 for those between 25 and 39.
Mrs Rose acknowledged that difficult financial times were also likely to have played a role in reducing road carnage. She said more people were practising "economy driving", including maintaining steady speeds and not roaring away from traffic lights.
"That's all good stuff. An economy driver is somebody who is really focused on their driving. A side-effect of that is a really good safe driver."
The police also had a range of new enforcement technology, including automated number-plate recognition in some areas, which helped them to home in on "vehicles of interest" such as those likely to be in the hands of drunk or disqualified drivers.
Hand-held licence scanners and long-range camera lenses were among their other tools.
Automobile Association spokesman Mike Noon said the organisation was "absolutely thrilled" with the lower road toll, although Kiwi drivers should not let it make them complacent.
"There's no resting on laurels - we're only just starting to get into the realm of where we want to be against Australia and the UK," he said.
"Last year, if we had been on Australia's rate we would have been under 300 [deaths]."
Mr Noon also believed people aged 45 to 59 were still dying at about the same rate and he fingered warm weather as a potential culprit behind the high Christmas road toll.