A young Auckland man has admitted a prolonged and vicious "racially motivated" road rage attack on a family which saw him ram their car off the road, sending two children flying through the air.

Fraser Milne, 21, appeared today in the High Court at Auckland before Justice Sally Fitzgerald where he pleaded guilty to dangerous driving, injuring with intent to cause grievous bodily harm and four charges of injuring with reckless disregard for safety.

He was convicted and will be sentenced in July.

In March last year a Chinese-New Zealand family, including their two children aged 12 and 10, were enjoying a day out picking blueberries near Auckland.

A family friend was also in the car.

However, as Milne was driving over a hill he passed the Chinese family's car.

He was forced to swerve to avoid a collision, believing the family had crossed over to his side of the road, and drove into a drain and struck a fence.

Milne then turned his car around and chased the family.

He passed them at speed before doing a u-turn to cut them off.

He then left his car to confront the family and demanded they pay for the damage to his car.

Milne, angry, shouting and swearing, also told them he belonged to a gang and was going to kill them.

The family attempted to call police but had trouble with the reception so returned to their car and left.

But, as they looked in the rear view mirror they noticed Milne following them, quickly catching up.

The family stopped their car due to Milne's erratic driving.

But Milne ramped up his threats as he approached the family's car with his blue-nosed pit bull dog.

Afraid, the family locked themselves in the car, while Milne began hitting the car and yelled that his dog was going to eat the family.

The family quickly drove away again.

However, Milne's rage would return after he went to a group of shops and vented his anger to several people present.

He said Asians were "taking over the country" and "f**king Asians" had damaged his car.

Milne also made a racist remark about the shape of the family's eyes and said they had run away because he would get "the pieces of sh*t" deported.

While Milne was carrying out his racist tirade at the shops he spotted the family driving past.

He quickly returned to his car and gave chase, driving at such a speed he caused his wheels to spin and narrowly avoided hitting another car.

Milne chased the family for about 7km and reached speeds of 140km/h.

After catching the family he pulled up alongside them on the wrong side of the road.

After demanding the family pull over he deliberately rammed the family's car, causing it to spin out of control, crash into a bank and flip in the air.

The family's car landed upside down on top of Milne's car before sliding off when Milne braked suddenly.

The two children were thrown from the car during the crash after they had taken off their seatbelts, frightened of Milne, and believing they might need to exit the car to run.

They narrowly avoided going down a steep ravine, which was about 100m deep.

Despite the two children lying injured on the road, Milne approached the car and continued his racist attack.

"Get out of the f**king car, I'm going to smash you! You f**king Asian c***! F**king Asians!" Milne yelled.

Locals arrived shortly after and Milne yelled out to his dog.

At no time did Milne attempt to offer assistance to the family.

The family were all taken to hospital, with one of the children transported to Starship Hospital by the Westpac Rescue Helicopter with an undisplaced fracture to his skull, a laceration to his scalp and a small subdural haematoma.

The family friend also suffered a spine fracture.

When Milne was questioned by police he said he could tell the family weren't citizens and that they were "Asians that have lived here".

He also said he presumed they were on an "illegal visa" and "Asian mafia" who had spent "two days in the country".

Milne told police he was "at boiling point" when he saw the family drive past him at the shops and that "any Asian in general [he] wanted to hurt".

He admitted to taking out the family's car and said he had "so many emotions rolling through [his brain]".

When Milne rammed the car he thought, "someone's gonna come out of it dead" and "this is it ... if they wanna kill me, let them kill me".

He also admitted he "felt like killing" the father of the family and wanted to "grab his neck and strangle him".

Crown prosecutor Jasper Rhodes said the incident was a "very serious racial motivated attack on a family".

"Everyone is incredibly lucky that nobody came out of this dead."