A coroner's inquest has heard that an overseas student was driving on the wrong side of the road before colliding head-on with a logging truck near Tokoroa in February.
Julia Lee, 20, and her parents Warren and Aesoon were killed instantly while her 17-year-old brother Griffin died of his injuries a week later in Waikato Hospital.
Mr and Mrs Lee were American citizens living in Hong Kong and had flown to New Zealand to help their daughter get ready for her studies at Auckland University.
Crash analyst Constable Bayley Orr told the inquest on Thursday she believed the chances of someone surviving would have been much greater had they been wearing seat belts.
"The left-hand side of the Toyota was relatively undamaged so if an occupant had been belted into the left rear seat the injuries could have been much less significant," she said.
She believed Ms Lee was driving on the wrong side of the road for some time before colliding with the truck.
When asked by coroner Gordon Matenga if the driver could have unintentionally crossed the centre line on State Highway 1, Const Orr said: "I believe it was intentional because she thought she was driving on the right side of the road."
New Zealand Transport Agency spokesman Jim Harland said statistics revealed foreign visitors accounted for just six percent of fatal accidents last year.
"The perception has emerged from the last summer season where there was quite a lot of high profile exposure given to crashes from overseas licence holders," he said.
"There is always a risk that the sensational reporting can make its way into international media and last year's key-taking incident that occurred did resonate around the world.
"It's not really appropriate behaviour and not consistent with New Zealanders being good hosts for visitors in their country," he said.