GOT IN CAR TO DRIVE, DRIVER SEAT WARM (THOUGHT DUE TO PARKED IN PHOENIX SUN). BUT WITHIN 10 MINUTES UNBEARABLE HEAT DRIVER SEAT, NEEDED 2 PADS TO PROTECT. SEAT HEATER WAS OFF, NO LIGHT, BUT I TOGGLED SWITCH TO SEE IF HELP, IT DID NOT. CAR PARKED AT WORK 15 MINUTES AFTER STARTING JOURNEY. 2 1/2 HRS LATER PERSON IN PARKING LOT NOTED SMOKE COMING FROM INSIDE CAR, CALLED FIRE DEPARTMENT. THEY NOTED INSIDE FULL OF SMOKE AND GLOW UNDER DRIVER SEAT. OPENED DOOR TO EXTINGUISH FIRE AND CAR BURST INTO FLAMES ALA THE MOVIE BACKDRAFT. ENTIRE INTERIOR MELTED. *TR