SITTING IN THE CAR, ENGINE RUNNING; HAD PULLED OVER FOR A COUPLE MINUTES TO LET PASSENGER OUT. NOTICED SMOKE STARTED TO SEEP OUT FROM ENGINE. CHECKED TEMP GAUGE AND SAW IT WAS COOL. TURNED OFF ENGINE AND MOVED AWAY FROM THE CAR IMMEDIATELY. AFTER A MINUTE OR TWO, SAW FLAMES COMING OUT FROM ENGINE COMPARTMENT. CALLED THE FIRE DEPARTMENT, THEY ARRIVED WITHIN A FEW MINUTES AND EXTINGUISHED THE ENGINE FIRE. ENGINE, FRONT TIRES, EVERYTHING IN ENGINE AREA COMPLETELY DESTROYED BY THE FIRE. PRIOR TO THIS, NO PROBLEMS, NO ENGINE LIGHT LIT, NO UNUSUAL SOUNDS OR HANDLING OR SMELLS, NOTHING TO INDICATE ANYTHING WAS WRONG.