The son of the man killed in an "appalling" road rage attack says the perpetrator has not shown true remorse.

On his daughter's third birthday, Bio O'Brien, 28, was jailed in the High Court in Auckland today for three years for the manslaughter of Jasmatbhai Patel, 78, in the Auckland suburb of Mt Albert on April 7.

After their two cars were involved in a minor collision, O'Brien dragged Mr Patel from his vehicle and attacked him.

Mr Patel fell and hit his head. He died in Auckland Hospital the next day.

Justice Judith Potter said the starting point of four and a half years was reduced to three years because of O'Brien's early guilty plea, expressions of remorse, and an offer to meet his victim's family.

But Mr Patel's family said they did not want a meeting.

And after sentencing today the victim's son, George, said he did not think O'Brien was truly remorseful.

He said no sentence would be enough, although he respected the New Zealand justice system.

In his victim impact statement read to court, George Patel said his father was not an ordinary man.

"He was the most loving and caring dad."

When George Patel's mother died 20 years ago, he had promised to care for his father.

"His death felt like I lost a personal part of my life."

He said he drove past the spot his father was killed on Carrington Road every day.

"I will never again see or talk to my Dad. It makes me sad and distressed when I see violent acts on telly - I feel my Dad died the same way."

He said he did not wish even his worst enemy to die the way his father had.

His father was a very successful businessman in India and moved to New Zealand for a better life for his family. "He was a kind person who always put others before himself."

The court heard O'Brien and Mr Patel were both driving south on Carrington Rd when Mr Patel's car dented O'Brien's BMW.

O'Brien went to Mr Patel's van and pulled him out to look at the dent.

He pushed and pulled Mr Patel by his shirt and struck him on his face and chest.

He pushed him over and Mr Patel's head hit the kerb. He bled profusely from his left ear and his eyes rolled backwards.

O'Brien moved Mr Patel to the grass and waited for police to arrive.

Police prosecutor Nick Malarao told Justice Potter O'Brien's sentence should be a deterrent for similar offences.

He said O'Brien was physically bigger than his vulnerable 78-year-old victim.

Defence counsel David Niven said O'Brien expressed remorse as soon as he realised what he had done.

In his statement to police, O'Brien said as soon as Mr Patel hit the ground, "I realised what I had done and tried to assist".

Justice Potter said she did not take into account O'Brien's prior convictions for male assaults female and threatening to kill in 2001.

She said it was an "appalling case of what may be described as road rage."

Driving in Auckland could be frustrating but O'Brien's actions were "totally disproportionate" to the incident, she said.