Police said dozens of complaints were received about reckless and dangerous driving during the procession, which included 100 motorcycles and 150 cars.
"The complaints included vehicles being driven on the wrong side of the road, intersections being blocked, passengers sitting outside vehicle windows, dangerous overtaking, motorcyclists not wearing helmets and sustained loss of traction in close proximity to pedestrians."
Nearly 300 infringement notices had been issued to motorists for dangerous driving offences. The investigation was ongoing, including a review of footage of the procession.
"Many of the drivers in this procession presented a very real risk not only to their own safety and their passengers, but also to other road users and our wider community," said Waitematā East Acting Area Commander Simon Walker.
"This type of behaviour on our roads will not be tolerated by police and our community."
On the day, police monitored and filmed the procession, including observers from an Eagle helicopter.