Brandon Wright, 21, had been flown to Intermountain Medical Center in Murray shortly after his motorcycle collided with the car Monday on U.S. Highway 89 in Logan, the Salt Lake Tribune reported.
Police said Wright and his motorcycle slid under the car, which had pulled out of parking lot into Wright's path.
Ruptured gas lines caused the car to catch on fire and a number of bystanders braved the flames to lift the car and pull Wright from underneath, police said.
Wright suffered broken bones, cuts and burns, Assistant Logan Police Chief Jeff Curtis said.
The driver of the car was not injured, he said, and no charges had been filed as the accident was still under investigation.