Firefighters were called to the parking lot at the Thailand Post office in Rawai, located just south of Chalong Circle, at 4:30pm, reported the Phuket Info Center.
Emergency workers arrived to find a green, Phuket-registered Volvo station wagon ablaze. Flames had engulfed the car, sending a plume of thick, black smoke into the sky.
Firefighters took just 10 minutes to extinguish the flames, but by that time the whole car had been heavily damaged by the fire, said the report.
No people were injured by the fire, firefighters confirmed.
The driver of the car, named by the report as Hans Ola Persson, told officers at the scene that he was driving to the Rawai Beach area when smoke started coming out from the engine bay.
He drove the car into the parking lot at the post office and exited the vehicle, a prudent move as flames quickly spread to the rest of the car.
Mr Persson said he had no idea what caused the fire.
The damage to the car was estimated to cost around B300,000 to B400,000.