Alessia Boschiazzo, 14, was visiting friends when she was struck by the speeding car in Marland Road on February 25. She spent a week in a coma but died in intensive care on Friday.
Detectives arrested the 21-year-old man on Monday night on suspicion of causing death by dangerous driving and arson.
The teenager, an aspiring dancer, was recently offered an audition at the renowned Brits Academy of the Arts in Croydon. She attended Ursuline High School in Wimbledon.
Alessia’s father, Aldo Boschiazzo, 44, said of her ambitions: “Ever since she was six-years-old she wanted to be a dancer. She was exceptional.”
Friends and family have written tributes to the teenager in a Facebook group. One member said: “They took such a beautiful and talented girl’s life away.”
Another friend said: “You were such a young and beautiful girl who really didn’t deserve this.”
The car, a green Renault Clio, was found burnt out by police in a nearby street.
Her father said: “Alessia was everything to us.”
Closed circuit television footage from a nearby garage shows the car changing direction to avoid Alessia, but he hit her before driving away at a high speed.