The results from the ministry's observational survey in October last year revealed that nationally 98% of children aged between 5 and 9 were in a child seat, booster seat, child harness or adult seatbelt.
Of the metropolitan areas, Dunedin was at the top of the list with a perfect 100%, with all 204 children surveyed being restrained.
Northern and Western Auckland also got perfect scores.
Southern Auckland was at the bottom of the metropolitan areas with 84% of 409 restrained.
Dunedin had the most children (40%) in booster seats, child seats and harnesses and Southern Auckland the fewest (8%).
Police figures released to the Otago Daily Times under the Official Information Act revealed a similar trend.
Police issued 137 infringement notices to motorists who had failed to restrain a 7-year-old in the first two months after a new child restraint law change.
The law change on November 1 required any child under the age of 7 to be properly restrained in an approved child restraint.
If the child is 7, an approved child restraint, if available, must be used, otherwise a safety belt, if available, must be used.
New Zealand Police issued 1572 infringement notices between November 1 and December 31 last year to motorists who had failed to ensure a child aged 7 and younger was in an approved child restraint.
Of those 1572 children, nearly 9% were aged 7.
The most infringement notices were issued in Counties-Manukau (24%) and Eastern (20%) police districts and the fewest were issued in Tasman (1.2%) and Southern (1.7%).
Plunket Otago and Southland car seat services manager Kathryn Impelmans said the perfect Dunedin score was ''positive'' and revealed caregivers were ''trying to do the right thing by their children''.
The feedback to Plunket was the children were happier in booster and child seats because they were more comfortable and had a better view out the window than when wearing an adult seatbelt.
Dunedin police road policing manager Senior Sergeant Phil McDouall said one person was ticketed in a Dunedin police operation this month for having a passenger, aged 15 or younger, unrestrained.
