WHILE DRIVING BACK FROM AIRPORT TRAVELING 15MPH STARTED SMELLING SMOKE FROM THE HEATER. TURNED OFF HEATER. PULLED UP IN THE DRIVEWAY AND TURNED OFF CAR. VEHICLE WAS FILLED WITH SMOKE UNDER THE HOOD. SMOKE GOT WORSE. WHOLE CAR ENGULFED IN FLAMES. IT WAS DETERMINED THAT AN ELECTRICAL SHORT CAUSED THE FIRE.*AK