You could pipe a large foam extinguisher into a couple places in the dash using hose etc....then in the event of a problem just trigger it and it'd fill the dash with flame retardant foam. Huge mess to clean up, but better than the car burning down IMHO.

Or, carry several different extinguishers. I need to get myself a couple Halon units for our cars....in addition to the normal auto-extinguisher. Can never have too many!

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