McMath said her nephew, who did not want to be identified, got out to find out why he had been targeted.
"Obviously that was the wrong thing to do."
He told her the driver, who appeared to be under the influence of alcohol or drugs, hurled a barrage of verbal abuse before suddenly striking him.
Before her nephew lost consciousness at least one another person had started to get out of the car.
"My nephew saw the passenger of the other vehicle get out, presumably to help his mate. That was the last thing my nephew remembered."
A neighbour who saw the vicious roadside attack unfold told a family member up to four people were bashing the driver.
During the brutal encounter the man was struck on his head before being left unconscious on the side of the road.
McMath said he had a huge knock to his temple, a swollen face and a sore chest and shoulder.
Her nephew has no idea how he suffered such widespread injuries to his upper body.
A passing pizza delivery man noticed the man lying on the footpath near his car and called emergency services. Other drivers also stopped to help, said McMath.
The injured man came to in the back of the ambulance as it travelled to North Shore Hospital.
He was due to return to Australia on Sunday to take up a new job but instead has been forced to wait until today before flying out.
Those who stopped to help the badly-injured man left slumped on the footpath are being lauded for stepping in to raise the alarm and waiting with him while help arrived.
McMath publicly praised their actions on Facebook community pages saying the family were grateful for their help.
"A heartfelt thank you to the members of the public who stopped to assist my nephew and contacted the police and ambulance," she said.
Since writing about the unprovoked attack on social media at least three other people had come forward saying they had also been targeted in similar incidents that night.
One woman was driving along Metcalfe Rd in Ranui when a group of men in a white car started following her closely behind and yelling at her. Another incident took place in Waimauku when a car attempted to run another vehicle off the road.
The man described his attackers as two young men, either Maori or Pacific Islanders in their 20s.
McMath said despite the ordeal her nephew was reluctant to make a complaint, preferring to get on with his new job across the Tasman.
Police confirmed they were called to the incident but because the victim did not want to lay a complaint no further action was taken.
