My Pops always told me that the fire extinguishers in the car/boat were not to put out your own car/boat fire, they were for the other guy's.

I mean, cars can be engulfed really fast and I doubt I'm going to be digging around for the exinguisher as much as getting myself and my 3 yo unbelted and the heck out of there.

I agree though that having them is a good idea, just for different reasons.