Because the offence was his second strike under the three strikes legislation, he must serve it without parole.
The court heard Atkinson had been drinking at Bason Botanic Gardens on the day of the accident. He drove from there to Castlecliff, where he had an altercation, went to two other addresses and left the last one in a car, with a female passenger in the front seat.
He drove toward Whanganui at speed, Justice Cooke said, weaving between lanes. The woman with him asked him to pull over, but he did not.
After the front right side of his car hit Gibbs on the scooter, he kept driving south. His passenger told him to go back, but he dropped her off after 1.3km and returned to Castlecliff.
On his return he attempted to hide the car, and used his T-shirt to clean blood off it. He was later found by police.
Atkinson had a difficult and traumatic life, the court heard. His mother is Te Ati Awa but he has had little iwi contact. His father was violent to his mother and his twin brother died.
Atkinson was drinking alcohol and using cannabis at 14. He was always thinking about alcohol and only truly happy when drinking it. It became his way of coping with trauma.
His education was limited, Justice Cooke said. He left school at 18 and was a father at 19. Now, aged 42, he has 11 children with five different women.
He has amassed 40 convictions for family violence, child sex offending, driving and driving while intoxicated. He has already served five prison sentences.
Reports said he was a good person at core but became angry and violent when facing difficulties and drinking alcohol.
Colonisation and deprivation were not enough to give him a significant discount on his sentence, but Justice Cooke made allowance for his remorse, alcohol dependency and willingness to meet the victims for restorative justice.
He disqualified Atkinson from driving for three years after his prison sentence ends.
Gibbs' family was not in court, and does not want reparations.