The daughter of a driving instructor who killed her teenage sister in a horror crash has been spared jail after a judge accepted no sentence could punish her more than her "incalculable" loss.
Criminology student Meliha Kaya, 22, was "far in excess of the speed limit" as she drove her 16-year-old sister Elif and a friend back from the George pub in Wanstead, east London, on February 13, 2016, experts believe.
Her Mini swerved on to the wrong side of the road, collided with a BMW and went over a low wall, hitting a tree on the 30mph Chigwell Road in east London at around 1.10am.
The teenager was found seriously injured and died at the scene. Her sister, then 19, was left in a life-threatening condition and spent weeks in hospital, the Old Bailey heard on Friday.
Elif was the only one wearing a seat belt and had asked to sit in the front seat for the journey, despite normally sitting in the back, prosecutor Julian Evans said.
Passenger Ayla Osman, 24, was also left with life-changing injuries.
On the day of her trial earlier this week, Kaya tearfully pleaded guilty to causing death and serious injury by her dangerous driving.
Judge Wendy Joseph QC sentenced her to two years in jail, suspended for 12 months, for the death, and 12 months for causing serious injury to run concurrently, also suspended for 12 months.
Kaya was banned from driving for four years.
The judge found that the speed at which the defendant had entered the bend where she lost control was "wholly inappropriate", but reduced the sentence from four years to two due to the guilty plea and injuries she sustained.
She told the court: "That is where it would have remained but for one last and overwhelmingly important feature.
"This defendant killed her sister and nothing she can ever do will repair that loss to herself and her family.
"I hope that she will do what she can to lead the sort of life her sister will have wished she would have been able to achieve, for both of them.
"I accept the grief she has been suffering is incalculable. No sentence I can impose can punish her as much as this."
Earlier the prosecutor said the joint opinion of the three experts was that the speed of the Mini was far in excess of the speed limit.
But Gudrun Young, defending, responded: "It is agreed evidence that she was driving far in excess of the speed limit but how far is simply, in my submission, not known."
She added one expert believed it could have been double the speed limit, an assertion disputed by the defence expert. It remains unclear what caused her to swerve suddenly, the court was told.
Neither sister had been drinking that night.
Kaya suffered post-traumatic amnesia and remembers nothing from the seven days before the crash, it was heard.
Her family begged the judge in victim impact statements to be as lenient in sentencing as possible.
Parents Nevzat Kaya and Demet Duzel said they did not hold their eldest daughter responsible, adding: "We have lost Elif and nothing can bring her back, but at least we can try and help Meliha live her life as best she can?.
"As the parents of Elif and as the parents of Meliha we ask the judge to give her the lightest possible sentence to encourage her to rebuild her own life."
The court was told the mother was a qualified driving instructor who helped teach Kaya to drive.
Youngest sibling Eda, 17, said: "Without her, I'm completely alone."
The emotional toll of the crash on the defendant and her family was set out in devastating detail to the court.
She suffers post-traumatic stress disorder and spent months sleeping in her parents' bedroom, often disturbed by terrifying nightmares, Ms Young said.
She continued: "She has felt fully responsible for her sister's death from the beginning. The sheer fact she was the driver and her little sister was under her care and she was responsible for her meant she has been wracked with guilt and blame over and above any criminal responsibility she may bare.
"She has spent the last two years tortured by knowing that she has caused her own sister's death."
The lawyer continued: "They were best friends as well as sisters. They shared the same friends and interests, they would go out together and there was an incredibly strong bond between them.
"They felt they didn't need anyone else but each other. Two young girls with real promise...all of that changed in an instance."
Following closely behind their car was Ford Focus driver Jordash Graham, who had met the girls in the pub and was following them back to their house. He was also speeding and crashed into the side of the BMW but was uninjured.
The 24-year-old from Leytonstone, east London, admitted dangerous driving. She was sentenced to eight weeks, suspended for nine months.
Judge Joseph hit out at the length of time it took for a prosecution to be brought and demanded an explanation.
The defendants were told they would face charges in October 2017, more than a year after the crash.
She said: "I'm going to sentence this lady for causing the death of her sister. Sitting in the court we have parents who lost their child.
"It is right to say that their grief is unassuagable and so is their anger in the way in which this has been dealt and I have some sympathy with that.
"I want a full explanation for how this matter could take as long as it did."
"It is the length of time I'm very concerned about," she added as she directed a written explanation be provided within 14 days.
Kaya, who lives with her parents in Woodford, east London, and Graham were allowed to go free from the dock at the Old Bailey on Friday.