The Los Angeles County Sheriff's Department says speed was a factor in the one-car crash that killed Fast And Furious star Paul Walker and a friend in Valencia, Santa Clarita, about 48km north-west of downtown Los Angeles.
Deputies found a 2005 red Porsche Carrera GT engulfed in flames when they arrived on Saturday afternoon.
According to entertainment-news website TMZ via MyPaper, the actor, 40, who made his name in a movie franchise about car racing, may not have got into the car that took him to his death if it had not been acting up moments before the crash.
Sources connected to former race-car driver Roger Rodas, 38, who had been driving, said he had been watching one of his employees try in vain to back the car into his car shop, but it kept stalling.
He then decided to take matters into his own hands and took the wheel, before Walker, saying he hadn't taken a spin in the Porsche yet, decided to hop in the passenger seat.
Walker and Rodas had attended a fund-raiser benefiting victims of a recent typhoon in the Philippines.