Ministry of Transport figures released today showed that during the past decade, no major drops in the road toll were sustained for more than a quarter - until this year.
Economic factors, fuel prices, law changes, safety improvements and policing were all likely influences on the toll, the ministry said.
There were also fewer three-day holiday weekends, as Waitangi and Anzac Days fell on weekends.
Road safety had also attracted a high profile in recent times.
Petrol prices in the first half of this year reached the record highs of 2008 - possibly leading to a decline in discretionary travel and fewer weekend deaths, the spokesman said.
Roads continued to be improved, with median barriers, passing lanes, realignment and rumble strips among the improvements.
Bans were also introduced on using mobile phones while driving, street racing and against repeat drink-drivers and drugged drivers.
Police had increased their numbers on the roads, cracking down on speeding and drink-driving and this was all reinforced by advertising.
Vehicles continued to improve, with the typical import now boasting better protection, electronic stability control and anti-lock braking systems.
However, increased motorcycle registrations were accompanied by more motorcycle deaths.
AA motoring affairs general manager Mike Noon said the fall in fatalities was fantastic but "what we all desperately want to see now is the trend continue in the second half of the year''.
"The lowest road toll we have had in the last five decades was 366 in 2008 followed by 385 in 2009 and 375 last year, so imagine how great it will be if we can go under 300.
"That would be 66 more people still alive to welcome in the New Year in 2012 and 66 families and friends whose lives haven't been devastated.''
The Government should focus on trying to understand why the toll had dropped, Mr Noon said.
The annual road toll this morning stood at 156, compared to 219 at the same time last year.
- NZPA