The Independent Police Conduct Authority is investigating a fatal police pursuit involving a group of teenagers who drove at speeds reaching 180km/h in two stolen cars.
Timoti Mohi was driving one of the stolen cars when the pursuit began at 12.50am on Wednesday in the Auckland suburb of Grey Lynn.
The 15-year-old died when he crashed the car into a power pole near the Market Road off-ramp on the southern motorway.
A male teenaged passenger is in Auckland Hospital with leg injuries.
The acting district commander for Auckland City, Chief Inspector John Palmer, says the stolen cars were being driven at reckless speed and were weaving in and out of traffic on the motorway.
Mr Palmer says Timoti Mohi's death, while tragic, was completely avoidable and the drivers should have stopped for police.
The driver of the second car and his passengers are still at large after abandoning the vehicle in Onehunga.
Police suspect a third vehicle was stolen so they could escape the scene.
The police serious crash unit is also investigating.
Last year, 19 people died while fleeing from police, compared with two deaths in 2009.
Wednesday's death brings the holiday road toll to 13.