I have been following the development of the foam fire extinguishers and there has been some improvements. The AFFF (Aqueous Film-Forming Foam) is getting approval from Underwriter's Laboratory, the U.S. Forestry Service, and many electronics groups, (as an alternative for Halon.) More of the foam formulations are biodegradable, less toxic to the environment, and just better overall, when compared to dry-power fire extinguishers. Only the Coast Guard has refused to accept it.
The only drawback I was able to find was that when compared to certain specific types of fire extinguisher media, in specific circumstances, you needed a larger volume of AFFF to do the same job as the dry powder fire extinguishers.
So, in general, the AFFF fire extinguishers are excellent for protection in a passenger vehicle.
I think it is rime to get the racing organizations to recognize the AAFFF fire extinguishers and change the rules regarding them.
Having said all this, has anyone bought one recently? They seem to be available only from overseas.