The incident happened around 1:30 a.m. Sunday near E. 102nd St and Avalon Boulevard in South Los Angeles.
The victim was sleeping in his car when a man poured some sort of flammable liquid either in or on the car then set it on fire, police say.
Firefighters arrived and put out the flames, finding a severely burned man inside. He was brought to a local hospital with third-degree burns. Later Sunday afternoon, police said the victim had died and the incident is now part of a homicide investigation.
Police believe the victim is homeless and was living in his car. No description of a potential suspect has been released.
Anyone with information is urged to contact police.