"Afterwards I was scared. I said 'he could have hit me.' It would have caused a major accident.
"I knew he was heading straight to me so I had to swerve . . . right after that my knees were trembling."
Millares thought the driver of the car might have fallen asleep at the wheel. He said they were not driving particularly fast, and had suddenly swerved over the centre line and into his lane.
He did not see what the car did after he passed it.
Millares has not reported the incident to police because he didn't believe anything could be done without a registration number of the other vehicle.
A police spokeswoman said motorists should call *555 if they noticed dangerous behaviour on New Zealand roads.
"This enables police to respond in a timely manner and manage the associated risks," she said.
"Motorists who use *555 regularly help police to make successful interventions which potentially prevent tragic incidents involving death and serious injuries on our roads.
"The *555 line is intended to report road incidents such as non-injury crashes, erratic driving, traffic congestion, breakdowns and obstructions on the highway.
"If you come across a genuine emergency where there is real risk to someone's life then we would always urge that you contact Police via 111."