"They got up to a little bit of mischief, a bit of a cruise. That's what teenagers are like."
Matthew, who owned the car, was thrown from the front seat as it rolled "about four times" and died at the scene, Sergeant Denis Tatere said.
His father was too upset to comment and the rest of the family were still in shock about the accident, said Mr Drummond. "It's pretty rough."
The crash happened after the driver oversteered, Senior Constable Corey Ubels said.
"The driver has steered off the road, through a drain, back on the road and the car has tumbled across," he said.
Mr Drummond said his nephew was a good kid who loved cars and was planning to become an engineer.
The 14-year-old male driver of the car was flown to Hawkes Bay Hospital in the Lowe Corporation rescue helicopter with moderate injuries, and later discharged.
A boy and girl in the back seat were "shaken up" and suffered minor injuries, Mr Tatere said.
On Thursday night, several Takapau residents arrived to comfort the friends and families of the victims, some standing in the middle of the road crying while looking at the wreck of the Holden.
One of the first to the scene was another of Matthew's uncles - a volunteer fireman who arrived to discover his nephew had died.
"It's the sort of thing you dread. You go to quite a few accidents and it's normally someone you don't know - but this was a bit close to home," he said.
Matthew was the son and grandson of two other members of the Takapau Volunteer Fire Brigade.
Fortunately, his father and grandfather were working and unavailable to be called out to the crash, Mr Drummond said.
He hoped his nephew's death would be a wake-up call for young people in the community to stop messing around in cars.
"It's young people having a bit of fun on the road and it's all gone wrong.
"As with every small town in New Zealand, young teenagers who think they're bulletproof take out cars to have fun."
However, Mr Drummond was concerned the accident wouldn't prevent similar accidents in the future.
"It might affect the community for a while and then the young fellas do it again."
Mr Ubels said police were gathering information from the scene and interviewing witnesses to "piece everything together" and formally determine the cause of the crash.