Police believe medical conditions may have affected the judgment of an 86-year-old man who caused a series of crashes as he drove the wrong way down Auckland's Northwestern Motorway.

The driver, today named as Ewen Donaldson of Tuakau, died in Auckland City Hospital overnight.

Police also confirmed Mr Donaldson held no valid driver's licence.

The 86-year-old's licence expired in 2007.

His passenger, a woman in her 60s and believed to be his partner, was killed when she was thrown through the windscreen of the green Mitsubishi Galant, landing under a 4WD vehicle.

Police have not made her name public as they attempt to contact her family in the Philippines.

The couple entered the motorway on the Te Atatu offramp, ignoring "Wrong Way" signs.

They were believed to be going home after an evening of line-dancing.

Mr Donaldson drove about 1km down the inside lane, colliding with a Ford Falcon and two 4WD vehicles.

Three other cars also crashed as they swerved to avoid hitting him.

Five other people were taken to hospital with injuries not thought to be life-threatening.

Sergeant Stu Kearns of the Waitemata serious crash unit said yesterday they had been unable to talk to Mr Donaldson.

"What we have learned is that he has medical issues that may well have affected his judgment.

Preliminary blood tests had shown he had no alcohol in his system.

Kanti Patel was driving his Honda home with his wife and two daughters, aged 14 and 9, when he saw the Mitsubishi racing towards him.

"A few seconds before the crash, I just said, 'Oh my God', and the car hit us. I tried to slide my car into the third lane, which was empty ... You don't think about anything except how to stop the car and how to save yourself.

"The kids and mum, they're crying ... We couldn't do anything except wait for the car to stop - it was sliding upside down on the roof."

The family all escaped unhurt through the driver's side window.

Mr Patel said a man and his wife rushed over to help the family before moving on to other motorists.

Derek Watts, who was a passenger in his partner Diana Balham's car, narrowly missed a collision with the Mitsubishi and was unaware it had been involved in a crash seconds later.

"We were travelling along in the middle lane in a line of cars ... My partner indicated to turn into the fast lane.

"All of a sudden our car swerved back in again. I thought, 'What's happening?'

"Then I see the lights of a car coming towards us ... We were just turning into the path of the oncoming car. It was quite close."

Drivers aged 75 and over must apply for a new licence every two to five years. They present a medical certificate and, if recommended by a doctor, they must do a 30-minute road safety test.

* People who saw the Mitsubishi Galant before the crash about 8.30pm are being urged to call the police on (09) 481-0300.

Motor Mayhem
* May 2010: Three people were arrested after police chased a stolen car with burst tyres as it fled along the Northwestern Motorway and rammed into a fence just past the Te Atatu off-ramp.

* November 2008: Two men fleeing police after stealing baseball caps drove 5km the wrong way from Westgate to the Lincoln Rd on-ramp before crashing into another car.

* April 2008: Odette Thompson died after driving about 10km the wrong way, from the city to Te Atatu, before hitting two cars and crashing into a ditch.

* June 2005: A man lost an eye when his car collided with a vehicle under the St Lukes overbridge after travelling the wrong way on the Northwestern Motorway.

* October 1999: Two cars dangled 15m off the Patiki Rd off-ramp after an elderly driver mistook it for an on-ramp.

- with NZPA