I have an Element mounted in all of my vehicles. I mounted them on the seat adjuster or rail (depending on power seats or not). It keeps them literally at hand in case of an emergency.
I got to test their effectiveness on my all original '29 Woody about a year ago when it had an under dash fire. That is not good in any vehicle. But, even worse when the gas tank is mounted on the firewall with a gas gauge that fills with gas to read. Of course, being a Woody, I could have roasted marshmallows if it went up.
Anyway, it was very effective in putting it out. It is also harmless to electronics and leaves no residue. I Like that it has a roughly 50 seconds discharge vs a 5-10 second small fire extinguisher. Plus you do not have to hold a trigger to use. So, you can drop (or prop) it in place and walk away to call for help. They also never expire.
(I completely stripped the Woody of all wiring and rewired it after the fire for anyone who was concerned

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