I've always carried a fire extinguisher in my car/truck and tractor since I had a car fire back in 1996.  I was on the way from daytona to ocala coming back from a day at the beach.  It was a hot summer, ac on max, radio going, etc.and traffic was flying down state road 40.  If you wanted to pass in the passing zones you had to do 90.  I pulled up to the first stop light in town, and noticed the car was stuttering.  I pulled of fthe road into an auto zone store.  I popped the hood with the car still going.  At that point the car shut off, and fire erupted from the alternator.  Before I could even move, the store manager was out there with a fire extinguisher.  The fire was insistant about not going out, as it was still being fed by heat from a melting wire hooked to the battery.  Amazingly enough, a tow truck pulled in beside me, and the guy jumped out with a pair of vise grips and pulled the battery cable loose.
This all took place in under a minute...  Needless to say,  I bought a replacement alternator from the store, and the tow truck guy gave me a great cash deal on the short tow down the road, as he was just comming off a call and was going home anyway.
About half an hour later I installed the new alternator and found that the pigtail harness is what caused the fire.
Ford must have known about this as the new alternator came with a *new* pigtail harness.. go figure...
So anyway, now i carry an extinguisher.. not so much for myself.. but maybee one day I can return the favor to someone in need, as others helped me in the past.
Soundguy