It was trialled in the wider Auckland region, including the North Shore, Waitakere and Counties Manukau.
Figures obtained under the Official Information Act revealed Waitemata had the highest number of offending drivers with 4672 warnings issued followed by Counties Manukau with 3169 warnings. Auckland had the lowest with 1768 warnings issued.
The worst offenders were drivers who exceeded 50km/h, passengers who didn't wear seatbelts and careless drivers.
Other offences included using a mobile phone while driving, unrestrained young children, no warrant of fitness, failing to comply with traffic signals and making a prohibited right or left-hand turn.
Searle said police were still compiling figures on warnings issued around new give-way rules.
"Police feel drivers adapted well to the new rule and there were very few issues experienced," he said.
Police would examine the results to determine if driving behaviour improved. If it had, the scheme could be rolled out nationally, he said.
Dog and Lemon motoring editor Clive Matthew-Wilson said Australian research revealed fines did little to reduce re-offending.
"By issuing a warning instead of a ticket, the police can remind the driver to behave correctly without being seen as an enemy."
Educate, don't fine
Melanie McKay is usually a law-abiding driver but last month, on her way home from visiting the North Shore, she slipped up.
The account manager was caught driving 15km over the limit in a 100km/h zone on the Northwestern Motorway about 2pm.
When blue and red lights flashed behind, she expected a hefty fine.
But to her delight, she was pulled over and let off with a polite but stern warning.
McKay said the warning system was a good way to change drivers' behaviour and educate people about road safety.
"If I was seriously being an idiot, I shouldn't have got a warning but I was only 15km over and I really appreciated it," McKay said.
The warning had made McKay more aware of her driving and her speed. She said warnings should be given to first time, low-level offenders only, and not repeat offenders.
Have you been warned? Email letters@hos.co.nz