Police pulled over a vehicle carrying 13 people and found only two wearing seat belts just before Christmas.

Waitemata road policing manager Inspector Trevor Beggs said there were five adults and eight children in the car, but only the two adults in the front seats were wearing seat belts.

"It was Christmas week, and a large 4x4 heading north out of Auckland," he said.

"There were seven seats in the vehicle and it was not suitable for 13 passengers. The driver was held accountable for the unrestrained children in the vehicle."

He said police were shocked by the "poor decisions made by adults in the group that put everyone in danger".

Advertisement

""I don't even want to think what the outcome would have been if they had been involved in a crash," he said.

"Thankfully, such examples are rare, and in this case early intervention by police prevented a possible tragedy."

He said there were 100 deaths last year associated with people not wearing seat belts, and 92 the previous year, which was "very disappointing".

"We're so much more aware these days of how a seat belt can prevent serious injury or death in a crash - so why are we not using them?" Beggs says.

Front-seat occupants had a 60 per cent reduction in the risk of sustaining a fatal or serious injury if they crashed while wearing their seat belt, and rear-seat passengers had a 44 per cent reduction.

"No one gets into a vehicle expecting to crash," Beggs said.

"But we know people make mistakes, so why would you not take all steps possible to prevent harm coming to yourself and passengers in your vehicle? It takes two seconds to buckle up, and it could save your life in a crash."

Auckland Transport, which was supporting the campaign by reminding people to "buckle up buttercup" through radio advertising and giveaways, wants the increase in deaths associated with non-restraint use to stop.

"From 2012 to 2016 there have been 61 unrestrained vehicle deaths," said walking, cycling and safety manager Kathryn King.

"That is far too many. Putting on your seatbelt, and ensuring all of those in your vehicle do too, is a simple thing you can do to keep yourself and those you love safe.

"Drivers make mistakes, a seat belt could be the difference between surviving that mistake and not, so buckle up buttercup."

Automobile Association spokesman Barney Irvine said recent signs that seat belt non-compliance was on the rise were alarming:

"We thought the issue of seatbelt use was largely done and dusted, but recent data suggests we've got a way to go yet.

"Buckling up is one of the simplest things drivers can do to keep themselves and their families safe, and we strongly support this effort to get the message out there."