WHILE DRIVING DOWN ROAD, SMOKE STARTED TO COME OUT FROM CENTER OF DASH, PULLED VEHICLE OVER AND TURNED OFF IGNITION, EXITED DRIVERS SIDE AND PROCEEDED TO PASSENGER FRONT TO INSPECT UNDER DASH, WHEN GOT TO PASSENGER SIDE (10 SECONDS FROM DRIVER SIDE) COULD SEE FIRE UNDER DASH AND PLASTIC DRIPPING FROM UNDER DASH, GOT AWAY FROM VEHICLE, AND WITHIN APPROXIMATELY 2 MINUTES ENTIRE INTERIOR OF VEHICLE WAS ENGULFED BY FLAMES. I WAS DRIVING AT NIGHT WITH HEADLIGHTS ON/ NO FOG/S, AND ONLY HAD FAN BLOWING OUTSIDE AIR IN, NO OTHER ELECTRICAL ACCESSORIES RUNNING, SUCH AS RADIO, INTERIOR LIGHTS). VEHICLE IS COMPLETE LOSS, AND FIREMAN SAYS THIS WAS WORST CAR FIRE HE HAD EVER SEEN FOR SHORT AMOUNT OF TIME VEHICLE WAS ON FIRE. SO FAR INSURANCE COMPANY IS INVESTIGATING, BUT INDICATIONS SHOW ELECTRICAL FIRE POSSIBLY FROM IGNITION SWITCH, WHICH HAPPENS TO BE IN DASH BY HEATER CONTROLS. NO INJURIES OCCURRED W/ VEHICLE FIRE, VERY HAPPY THAT SEAT BELT DID NOT FAIL/STICK. ONLY HAD VEHICLE FOR 5 MONTHS, BOUGHT NEW AT PONTIAC DEALER, 5600 MILES. VEHICLE WAS 2004 PONTIAC GRAND PRIX GT2 W/ OPTIONAL LEATHER SEATS. *AK