The body has not been identified, and authorities did not say whether the victim was the registered owner of the vehicle.
The California Highway Patrol received reports of a vehicle on fire on the Glen Helen Parkway onramp to the southbound 15 Freeway in Devore at about 10:15 p.m. Upon arrival, they found the Porsche Cayenne engulfed in flames.
After the fire was put out, firefighters discovered a body. The body was burned so badly, officials will need to use dental records or DNA to identify the victim.
The vehicle is registered to a man who lives in Chino and works in the Long Beach area. Detectives said when they spoke with the man's family, they said he hadn't been seen since Thursday afternoon.
Authorities said a man was seen with the registered owner of the SUV leaving a shopping center in Long Beach on Thursday afternoon.
The man is described as being around 6-foot-1, 325 pounds with a short pony tail, possibly Hispanic or Samoan.
Authorities have not determined a cause of death.
"They're confident that this person was killed," Bachman said. "How this person was killed, that's not clear yet."
Anyone with information is urged to call the San Bernardino Sheriff's Department at (909) 387-3589.