Waitematā Rd Policing Manager Acting Inspector Michael Rickards said police were aware of the video which had been circulating on social media for a few days.
"Sadly, this video is a prime example of poor decision-making behind the wheel.
"Nearly a third of people who die on New Zealand roads are not wearing seat belts. It's a really simple message – restraints save lives.
"Being properly restrained is important for all occupants of a vehicle, including children. Even in a low speed impact it can cause a great deal of harm to an unrestrained child."
Police were making follow-up inquiries with the vehicle's registered owner.
Under New Zealand law, all children under seven years of age must use an approved child restraint appropriate for their age and size.
Children aged seven must be secured in a restraint if one is available in the vehicle.
Anyone who witnessed motorists driving dangerously could contact police on *555.
If the manner of driving is posing a risk to other motorists they should call 111.