MY 2007 GMC YUKON XL; SELF COMBUSTED WHILE PARKED IN MY DRIVEWAY. MY WIFE DROVE IT ON AN ERRAND, RETURNED TO OUR HOME, PARKED AND LOCKED THE VEHICLE. WITHIN 20 MINUTES OR SO, THE VEHICLE BEGAN TO SMOKE EVENTUALLY THE ENTIRE ENGINE COMPARTMENT CAUGHT FIRE. THE VEHICLE WAS PARKED, OFF, KEY WAS OUT AND THE VEHICLE WAS UNATTENDED. LUCKILY, THE HORN BLEW WHICH ALERTED US TO THE FIRE. OTHERWISE, ADDITIONAL PROPERTY LOSS OR INJURIES COULD HAVE BEEN SUSTAINED. WE HAVE A SECURITY CAMERA VIDEO EVIDENCE (FROM OUR NEIGHBORS SECURITY SYSTEM) OF THE ENTIRE INCIDENT. WHILE I AM UNCERTAIN AS TO THE EXACT CAUSE; STATE FARM INVESTIGATED THE VEHICLE AND IS GIVING A SETTLEMENT CHECK FOR THE ESTIMATED VALUE. THE TRUCK WAS EQUIPPED WITH A "WASHER FLUID HEATER" AND THERE WERE TWO RECALLS BY GM BECAUSE OF THE RISK OF FIRE.