The two teenagers who were sitting the boot were both thrown from the car and suffered life-threatening injuries. They were flown to hospital where they were in critical condition. Three others in the car suffered broken bones.
Inspector Mark Fergus said the journey was doomed from the start.
"A young, unlicensed driver, in charge of a severely overloaded vehicle, on a dark country highway was never going to end well. Every teenager that got into that car made their own decision. Any one of them could have stopped the chain of events that lead to their friends being left with life-changing injuries, by deciding to not get in the car and insisting that they contact someone to come and get them," he said.
"Any car ride where two passengers have to ride unrestrained in the boot should set off alarm bells. Add to that an unlicensed driver late at night, and any parent who received a call from their son or daughter would have come and taken them safely home. Sure, there might have been stern words in the morning, but that is far more preferable than the grief that such a crash has caused," Mr Fergus said.
The Waitemata serious crash unit was investigating the crash and while it was too early to say whether charges would be laid, alcohol was suspected as a factor.