Government transport officials are being urged to consider raising the speed limit on some motorway stretches - particularly in Auckland - to 110km/h.
A call by veteran motoring writer Peter Gill to raise the limit from 100km/h along "choice" sections such as the new Hobsonville motorway gained tentative support yesterday from the Automobile Association.
But it was strongly opposed by the charitable organisation Brake, which yesterday launched its first New Zealand Road Safety Week, as likely to lead to more "carnage".
AA spokesman Simon Lambourne said his organisation had already asked the Government for a strategic review of limits throughout the roading network to reduce guesswork for drivers faced with a confusing array of speed control.
That was particularly so on local streets and arterial roads, where drivers often had to rely on luck to spot varying speed limit signs, unless they had on-board GPS navigation systems.
The important thing was to match speed limits with road types, rather than to continue to widen the range with little apparent consistency.
"This is not a debate about increasing speeds - it's about working out what is the best speed for particular areas," Mr Lambourne said.
But although the result may be lower legal speeds in some local streets, there could equally be scope for raising the motorway limit, particularly in Auckland where 64 per cent of highways had a four-star safety rating.
"We think there is a strong case for debate about whether we could have 110km/h on the motorway in Auckland," he said.
Exceptions should remain around sites such as Spaghetti Junction and the harbour bridge, on which the limit is 80km/h, and through road works.
"We should be looking at roads and asking what their purpose is - the motorway system in Auckland has a purpose of getting high volumes of traffic across the region as quickly as possible and in a safe manner."
Mr Gill said raising the limit on some well-engineered motorway sections makes traffic flow more efficient, and improves safety by reducing driver frustration as a major contributor to road crashes.
"There are now stretches of road that can easily accommodate an extra 10km/h which would reduce driver frustration considerably," he said. "Doing so would bring us into line with Australia."
But Brake chief executive Mary Williams said last night that Mr Gill and other drivers could not cheat basic laws of physics, which meant that "the faster you are going, the less time you have to react to unexpected hazards and the bigger the force of impact".
"A small increase in speed leads to a much bigger increase in the distance needed to sop, no matter how good your brakes are. We need to build on that, not introduce measures which present a bigger risk to road users."
A Ministry of Transport spokesman said it was unlikely higher open-road speeds would be recommended under a pending speed management review.
The ministry said travelling unreasonably slowly caused one reported injury crash in 2010. The police say they target slow drivers, particularly over holiday periods, and impeding the flow of traffic is an infringement offence which can result in a $150 fine.
Open road limits
* Australia 100km/h to 130km/h
* UK 113km/h (may rise to 129km/h)
* US 89km/h to 129km/h
* Japan 80km/h to 100km/h
* France 130km/h on motorways (reduced to 110km/h in rain)
* Germany No general limit on autobahns, maximum of 130km/h recommended.
Ideal candidates include long sweeping stretches on
* The Hobsonville motorway;
* The extension to Kumeu of the Northwestern Motorway;
* Between Silverdale and Albany on the Northern Motorway; and
* The Ramarama straight north of the Bombay Hills on the Southern Motorway.