Horizons Regional Council, Plunket and the Whanganui Police have teamed up to check child restraints in cars.
Horizons roadsafe coordinator Glenda Leitao said there were two checkpoints in Whanganui last Wednesday with 122 (of cars with child carseats) having the restraints installed properly while 70 were installed incorrectly.
While that was an improvement on previous checks, Mrs Leitao said there was still a long way to go.
"A lot of people have trouble fitting them in cars," she said. Twisted and too-short belts and too-big seats were the most common problems, and Mrs Leitao said it was important to get it right so the restraints worked properly.
She said a lot of people were buying seats online and getting the wrong size. She recommended buying from an outlet which had a right-of-return policy.
The law says children aged seven and under must travel in a child restraint while it is children aged eight and under if there is a restraint in the car.
"The majority of people we talked to on Wednesday were quite happy to do the check," Mrs Leitao said.
A Plunket child restraint technician visits Whanganui once a fortnight, and Mrs Leitao recommended anyone with concerns about fitting child restraints call Plunket to make an appointment.