When the woman started to question the red vehicle's occupants about the validity of the stop, they said they had another job to do and sped off.
This is the second reported incident of this nature involving a red car with flashing red and blue lights with the occupants posing as police officers. The first incident occurred in the early hours of Saturday February 9. The vehicle was described as a red Mazda.
Police advised that most police stops were conducted by uniformed staff in marked cars.
If police officers are not in uniform then, if asked, they will produce identification which contains a name, photograph and police identification number.
Police want to hear from anyone who may have been stopped by this vehicle or who has any information about similar incidents.
Anyone with information is asked to contact the Whangarei police on 09 430 4500 or call Crimestoppers, anonymously, on 0800 111 555.