The driver of a vehicle, believed to be a truck, which hit a young woman on Auckland's Southwestern Motorway early yesterday is yet to be identified.

The 22-year-old was found dead on the motorway about 5.30am.

Senior Constable Karl Bevin of the serious crash unit said it was not being treated as a hit-and-run.

"It's more likely that the female has entered the motorway as a large vehicle's been passing so either she's collided with the rear of the vehicle or with the trailer, if there was one. If that was the case then the driver just wouldn't have seen it or felt it.


"It's likely, based on the injuries sustained and the pattern of injuries, to have been a larger vehicle as opposed to a smaller car.''

The woman had been at a New Year's party nearby before she was hit.

"We believe there was some argument prior so she might have been in an upset state-of-mind but we need to confirm that with family members.''

Her name would be released once all her next of kin had been notified.

She was the first person to die on New Zealand's roads in 2012.

The second came less than 12 hours later when a 59-year-old woman was killed as she travelled from Masterton to Alfredton on Route 52.

Sergeant Jymahl Glassey said her car had drifted to the right hand side of the road and collided with an embankment about 5:10pm yesterday.

The woman, who was from the area, was already dead when another motorist drove past her wrecked car.

It was not known what had caused the crash and no witnesses had been identified.

"There was nothing that stood out: it was a relatively easy piece of road, straight with a slight bend, and although it had been raining the road conditions were dry so it's very hard to know what happened at this stage,'' Mr Glassey said.

A total of 284 people were killed on New Zealand's roads in 2011 - the lowest annual road toll since 1952.

However, despite the annual figures being significantly down, already 17 people have died on the roads during the Christmas-New Year period - five more than the entire period last year.

The holiday period started at 4pm on December 23 and ends at 6am on January 4.

Witnesses to either of the 2012 road fatalities were urged to contact police.