Dhirren Singh Randhawa, 19, from Encounter Bay, is due to be sentenced in the SA District Court on Tuesday.
He pleaded guilty to aggravated driving without due care and leaving the scene of a crash at Goolwa Beach, south of Adelaide, on November 17.
Charlie Stevens died in hospital a day after a young driver performed a U-turn and struck him. (Matt Turner/AAP PHOTOS)
The circumstances of the tragedy were revealed during sentencing submissions.
Charlie Stevens, 18, and three friends were celebrating Schoolies at a Goolwa Beach shack owned by his family, the court was told.
They had flagged down Randhawa at 9pm to ask for a ride to Victor Harbor but he declined, explaining that he did not want to risk demerit points on his P-plates.
He performed a U-turn and struck Mr Stevens, causing irreversible brain damage. He died at Flinders Medical Centre the next day.
Randhawa drove away in "shock and disbelief" but stopped when he saw a police car and told them what happened.
In court on October 3, Randhawa addressed Mr Stevens' family, telling them that learning Charlie's life support had been switched off "was the most difficult thing I've heard in my life".
"To Charlie's mum and dad, seeing you on TV, talking about Charlie brought out deep sadness within me," he said.
"There's so much I'd like to say, but mostly I want to say I'm sorry. And I'm sorry Charlie."
Grant Stevens said "there is not a day when we don't shed a tear thinking about our son". (Abe Maddison/AAP PHOTOS)
In his victim statement, Grant Stevens told Randhawa he could "not possibly understand what you have taken from us".
"There is not a day when we don't shed a tear thinking about our son and how much we miss him," Mr Stevens said in court, with his wife, Emma, by his side.
"Charlie was a vibrant, caring, fun loving, generous young man with a love of life and plans for the future. Now all we have are the memories of him and that is not enough."
Jane Abbey KC, for Randhawa, urged the court to impose a suspended or home detention sentence.
She said his remorse was genuine and asked that his youth, "distinct lack of criminogenic factors" and absence of prior offending be taken into account when imposing a sentence.
Director of Public Prosecutions Martin Hinton KC said imprisonment was the only option, given the gravity of the offending, and the question of suspension would be a fine balance for the court to determine.
Randhawa faces a maximum 15-year prison term, and a minimum 10-year licence disqualification.
