WE WERE DRIVING ON I-40, 25 MILES OF KINGMAN, AZ. THE CAR SEEMED TO MISS, DASH LIGHTS BLINKED AND "SERVICE AIR BAG" APPEARED ON COMPUTER. WITHIN 30 SECONDS SMOKE WAS COMING FROM UNDER PASSENGER SEAT - PULLED OVER, FLAMES WERE NOW COMING OUT FRONT SIDE PASSENGER DOOR. THREE FIRE EXTINGUISHERS EXTINGUISHED FIRE. CAR TOWED TO KINGMAN. INSURANCE ESTIMATES AT $15,500. CADILLAC DOESN'T SEEM TO BE TOO INTERESTED. CAR WAS FULLY WARRATIED. INSURANCE HAS INFORMED US IT WAS AN ELECTRICAL DEFECT.*AK