I still remember a guy I went to high school with who had a nice looking Jeep Cherokee, this was 1996 BC (Before Cruiser). Long story short, he noticed smoke from under the hood while driving, and by the time he pulled off the road and got out, the flames started to spread and he had to watch it burn.
I have never needed mine for my vehicle (knock on wood), but have used them for a house fire years back. You can get them at any auto parts store and various sizes. Keep them easily accessible, you don’t want to find yourself searching for it buried someplace when you need it. I’ve had them mounted in various places, I used to have the front one mounted to the transmission hump next to the shifter. Since changing transmissions and carpet work, I have moved it to existing grab handle holes on the passenger A pillar.
Something we did on club rides was inform everyone where the fire extinguishers and first aid kits were in vehicles. We carry tools and spare parts for the “just-in-case” factor, and as old as our vehicles are and all the mods we do, protecting it and yourself is just one of those plain good ideas.