Halon 1211 (the most common kind of Halon fire extinguisher) is an excellent fire extinguishing medium for automobile fires, but it is on its way to being banned in the US. It's already banned in the EU. You can't buy new Halon 1211 fire extinguishers any more, but you can still get used ones refilled, at least for the time-being.
The current Halon-type substitutes for Halon 1211 are nowhere near as effective, and therefore not a good choice for automobile use.
CO2 fire extinguishers are excellent for gasoline and electrical fires, and don't leave damaging residue behind like dry chemical fires do. But, they're very poor for wood/paper/brush fires, they're heavy, and initial purchase price is very high.
Dry chemical extinguishers often do as much or more damage as the fire itself may do, especially when used on electrical or electronic equipment. The dry chemical residue left after the fire is extinguished pretty much ruins whatever it touches, even if the fire didn't ruin it.
Foam fire extinguishers are better than dry chemical extinguishers for automobile fires, especially gasoline fires, but not as effective on electrical fires. You also have to choose them carefully, because not all types of foam fire extinguishers are approved for extinguishing fires caused by gasoline or other flammable liquids.