The deaths came a day after the end of Queen's Birthday weekend, in which six people were killed on New Zealand roads.
In this morning's crash, two occupants of the car were killed, while the truck driver was flown to hospital with serious injuries.
The collision happened about 11.55am on State Highway 77 Waimarama Rd at the intersection with State Highway 72.
The Serious Crash Unit had been advised and an investigation into the crash was under way.
Over the weekend four drivers, one motorcycle passenger and a motorcyclist were killed in separate crashes, police said.
That is double the number killed over Queen's Birthday Weekend last year, and put the number of road deaths since January 1 at 170.
"Any death on our roads is one too many, so six people being killed over one holiday weekend is absolutely shattering for many whanau, families and communities," said road policing operations manager Inspector Peter McKennie.
"We've seen far too much heartbreak in our communities already this year as the result of tragedies on the road.
"Everyone has to play their part to stop more people being killed on New Zealand roads and reverse the devastating trend this year. We all need to be very conscious of the risks at all times when we are on or around the road environment."
Many more people might have been killed without enforcement and prevention efforts from police and their partners, he added.
"Most people behave safely on the roads most of the time, but it only takes one risky decision or moment of inattention to result in tragedy, including on the part of those who generally drive or ride in a safe manner.
"The actions of every driver and rider makes a difference."
McKennie urged everyone to be careful behind the wheel, especially with winter setting in.
While there was no silver bullet, McKennie said drivers could help keep the roads safe by:
• Not being distracted
• Driving in a manner and speed that let them respond to the unexpected
• Paying close attention to changing conditions
• Never driving tired or substance-impaired, and
• Making sure everyone in the car was buckled in or in a child restraint.
