A driver with two children in the car passed a line of seven vehicles at 150km/h because they were driving too slow, police said.

The woman was stopped about 7pm last night between Dunedin and Milton after a police officer saw the vehicle passing at high speed on State Highway 1.

Police said when stopped, the 28-year-old Queenstown woman admitted speeding, saying she was sick of waiting in line as the other cars were driving too slow.

She was driving with her husband and two young children to a relative's address in Waitati.

The woman received a 28 day licence suspension, 50 demerit points, and infringement notices for the excessive speed, driving on an expired licence and in an unlicensed car.

Acting Senior Sergeant Craig Dinnissen said passing lanes are not a drag strip, and passing must be completed at a safe speed, below the speed limit.

Police are enforcing a reduced speed tolerance of 4km/h during the Easter weekend, as well as breath testing and other enforcement measures.

The official Easter holiday road period runs until 6am on Tuesday, April 7.

Last year's Easter road toll was five, from a reported 95 injury crashes.