"They take it all in. It goes down so strongly with the kids," she said.
Mr Cheyne said the effect it had on some young people, who later got close to wrecked vehicles and portrayals of the physical and emotional results of crashes too often caused by speed and alcohol, was sometimes clear to see.
"We see some showing some real emotion," he said, adding that talking to the youngsters revealed they had been through the "ripple effect" of a crash involving someone they knew.
"They realise very well so many people are affected."
That was the message he hoped the expo would get through to tomorrow's young drivers on the roads.
This year's expo featured a new section focused on the ripple effect, detailing the financial and human costs of serious crashes.
Hawke's Bay Hospital Emergency Department nurses had voluntarily given up their time to man a stand as part of the section, which greeted the young visitors with the hard reality of where an otherwise avoidable driving mistake could end up putting them - it was a coffin and flowers.
"They [student groups] are only in here for two hours but in that time we can only hope we can get the message through about what can go wrong," Mr Cheyne said.
Fifteen-year-old Amariah Luki from St John's College, who said he wanted to get his licence when he turned 16, was impressed.
He said: "It's really good because it makes you think. It has taught me a lot of things."
The expo is open again today from 11am to 1pm.