Jenni Larsson, 22, was a passenger in the alleged racecar, which smashed into another vehicle that was crossing an intersection in Östersund, northern Sweden, on Saturday night, reported the Aftonbladet newspaper.
The collision also claimed the life of a 19-year-old Swedish woman who was a passenger in the other car.
Larsson’s fiancé was the first on the scene, discovering Larsson unconscious.
“I was in a car some distance behind. I saw everything, it was brutal,” he told the paper.
Police had earlier been anonymously alerted when a worried driver reported that they had been overtaken dangerously on the highway.
“The person had been overtaken by several cars at very high speed,” said Eva Posner-Storm, of the Östersund police, to the paper.
“We have launched a preliminary investigation into the possibility of aggravated reckless driving and involuntary manslaughter,” said Posner-Storm to Aftonbladet.
The police are yet to speak with the other three passengers who survived the accident.
Meanwhile, Larsson is survived by her four-year-old daughter.