The "remorseless" O'Sullivan will join his brother Adam O'Sullivan, Lawrence, and Jesse Ellmers in prison, who were each sentenced to two years and three months' imprisonment for their involvement in the race.
"Justice, I think has been done," Maree's grandfather Bruce Fiveash told Hawke's Bay Today yesterday.
"Nothing is going to change what happened ... but there is closure in some ways."
Judge Jonathan Down said during sentencing that a late letter of remorse from O'Sullivan was "too little, too late" and was in stark contrast to the pre-sentence report which stated that O'Sullivan showed a "lack of insight into [his] involvement".
"Your attitude is one that is characterised as lacking insight and lacking remorse to the extent of almost blaming other people for what happened on that night," Judge Down said.
"He hasn't quite realised what he has done," said Maree's grandfather, who, with his wife, Maureen, raised the teenager from a young age.
"I'm still really pissed off, I'm angry but that's not going to change it," Mr Fiveash said.
"Nothing is going to bring back Maree."
He hoped the tragedy would force young people to think twice before making "stupid decisions".
"At the end of the day all I can hope for is that young people realise they can go to jail now if they want to go do something stupid like street racing."
When asked about O'Sullivan possibly appealing his sentence, as his brother and Ellmers had, Mr Fiveash said: "We can't control what happens after this."
Their appeals were dismissed at the High Court in April.
He said Maree, who was due to start a hairdressing course at EIT the day after her death, will continue to live in the memories of her family, who recently placed a headstone over her grave, a place Mr Fiveash sadly calls "her home".
"It's the only place our family can go and visit her now, that's the only place that is home for Maree.
"We've done everything we can to make sure she remains in our hearts and minds."
Maree's mother also read an emotional statement to the court yesterday, explaining how "unnecessary stupidity" robbed her daughter of "dreams [for] a 21st, a wedding, and maybe one day children".
Maree's death "has changed a lot of lives" but ultimately "we have lost a family member forever".
She displayed apparent anger towards O'Sullivan when she said: "We don't call it an accident because it was planned."
Crown prosecutor Steve Manning said: "All who took part in the race were dicing with death.
"It was an act of utter stupidity that has endured with the most serious of consequences."
Justice has been done - family
All who took part in the race were dicing with death. It was an act of utter stupidity.
Crown prosecutor Steve Manning said "remorse was not available" for O'Sullivan as a possible discount on his prison term because the 21-year-old "simply refuses to accept [responsibility]".
O'Sullivan's lawyer, Scott Jefferson, said the tragedy was a result of "the failures and shortcomings that often come with youth" and the false perception of "indestructibility" teenagers hold.
"It is obvious to say there was an absolute failure to think ahead and see the consequences of [O'Sullivan's] actions," Mr Jefferson said.
Judge Down said a jury simply refused to believe O'Sullivan when he attempted to extirpate his guilt in the tragedy by saying he braked and slowed down, well ahead of the next intersection, which was the designated finish line.
O'Sullivan "aggravated [his] offending" because he was disqualified from driving at the time of Maree's death and had also been convicted of sustained loss of traction while driving in the past, Judge Down said.The judge also disqualified O'Sullivan from holding a driver's licence for four years.
The four young men responsible for Maree Schafer's death were the first in the country to be sentenced under tough new legislation against boy racers with the Sentencing (Vehicle Confiscation) Amendment Act and the Land Transport (Enforcement Powers) Act.
