The local (to you) FD may take the gas mix, for just this reason.
Christopher A. Young Learn more about Jesus
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You can also bend and weld up a 4X4 burn pan out of 1/8" Plate and invite the neighbors over to practice Fire Extinguisher techniques.
There is nothing that builds confidence more than actually doing it - then they'll know what to expect when the real thing happens, rather than just run away and watch the house burn down.
Be sure to have them bring whatever they have around the house to the practice round. Someone will bring a few crappy Plastic Head Kidde's, I'm sure you'll try to blow them off and find at least one dud that doesn't work in the pile. Let that be a lesson that you can't buy crap if it has to work in an emergency.
Get a pile of business cards from a local Extinguisher Shop, and work out a nice price for Amerex 417's (or other quality units) for cars, and 500's or bigger for house and garage.
$35 2.5# extinguisher, $20,000 car - a few $40 5# extinguishers, a $1M house - both seem like a no-brainer to me...
And when everyone's had their turn and there's still gasoline left...