OWNER'S SON WAS DRIVING VOLKSWAGEN AND IT STARTED OVERHEATING. DURING THE COURSE OF THE EVENING, HE TRIED A FEW TIMES TO LET CAR COOL DOWN AND THEN CONTINUE DRIVING, BUT THE ENGINE WOULD CONTINUE TO OVERHEAT. HE MANAGED TO CONTINUE DRIVING AND NOTICED SMOKE COMING FROM THE BACK OF THE VOLKSWAGEN. HE SHUT THE ENGINE OFF AND COASTED TO A STOP. HE GOT OUT AND NOTICED SPARKS DRIPPING FROM UNDERNEATH THE VEHICLE. THE VEHICLE BECAME ENGULFED IN FIRE. CAUSE UNDETERMINED, BUT SPARK PLUGS SHOWED EVIDENCE OF A RICH AIR/FUEL MIXTURE. *NM