Jimmy Martin Brito, 34, was travelling at 136km/h when his Subaru spun out of control and slammed into a tree in Sydney's south in August 2023.
The passengers of the vehicle, two brothers aged nine and 10, died in hospital soon after the crash, while a nine-year-old girl survived with minor injuries.
Brito exceeded 140km/h at times as he and a second driver weaved in and out of busy Friday night traffic in Sydney's bayside suburbs.
Words could not describe the "utter destruction" of the car after it hit the tree in Monterey, Judge John Pickering said as he expressed shock it was not worse.
"It is in some ways a miracle only two people died in the collision - as horrendous as that clearly is," he said.
The judge was scathing of the offender's conduct, describing it as a very serious example of manslaughter and referencing another killer driver Samuel William Davidson, who killed four children walking home in 2020.
The ad hoc street race had no obvious start or finish line and the drivers appearing more focused on who could be faster, a little more reckless and who pushed the limits.
"In one respect ... it was a show-off between the two of them," the judge said.
Brito, who was unaffected by drugs or alcohol and drove at varying speeds over an eight-kilometre route, must have known his degree of driving was so poor that "inevitably people at most risk were the three young passengers" in his car, the judge said.
The nine- and 10-year-old victims would have had no concept of the danger and reality they were put into by Brito, let alone the strength to pull a handbrake to save themselves.
The surviving girl told the court she experienced nightmares, faced stress of being an ongoing witness in the court case and had been unable to celebrate birthdays or Christmases with her deceased best friends.
"I'll never forgive him for what he has done or ever face him again," she said of Brito.
Judge Pickering also acknowledged the pain "the selfish acts of the offender" had caused to the boys' parents and step-parents.
Brito's sentence was mitigated by some evidence of remorse and rehabilitation - alongside his known physical health, mental health and cognitive issues, and time in protective custody.
His term was cut by another 35 per cent in recognition of his early guilty plea and a recent agreement to give evidence against the other driver in his August trial.
Adam Yurun, 25, is contesting charges of aiding and abetting the boys' manslaughter.
While not critical to the prosecution case, the Crown acknowledged evidence about the continuity of the so-called race would be important.
With discounts, Brito was ordered to serve at least eight years in prison, backdated to the date of the crash when he entered custody.
His full 11-and-a-half-year sentence ends in 2035.