Q:

Is it worth having a fire extinguisher in the car? 

I've always had a small 1 Kg (2.2 pounds) multipurpose ABC dry chemical fire extinguisher in the car.  It has finally expired and I'm wondering whether I should get a new one. 
In my region it is not mandatory to carry one and, I've heard several stories, that to put out a car fire, 3 full extinguishers had to be used.  This makes me wonder whether a small 1 Kg extinguisher is even worth keeping in the car. 
Should I still have one?  Are there occasions where it would help? 

A:

If you feel you would like to get a new extinguisher, I'd just suggest you get one to replace the old one.  Buy a bracket to hold it down and mount it some place where you have easy access.  
The reason I say this is because almost exclusively the fire extinguisher will not be used for your vehicle, but for someone else's vehicle.  Will a 1kg extinguisher put out a fire?  Maybe not, but it could give you enough time to save someone's life.  
The only caveat would be if you can afford it, but extinguishers are not too expensive.  Do as you feel as right, but how bad would you feel if you actually needed one and didn't have it. 

A:

If it were that important, cars would come standard with one.  As it is, the only road-going car I know of that comes with a fire extinguisher as standard is the Porsche Carrera GT3.  And that's only because it's a thinly disguised track car, complete with roll cage and barely legal tires. 
It doesn't hurt having a fire extinguisher in your car, but you have a much greater chance of dying because the fire extinguisher brained you in an accident than dying in a fire caused by said accident (Unless you go through the trouble of securely fastening it somewhere that is both out of the way AND easy to reach in case of a fire).  Cars very rarely burst into flame.  And when they do, you'll have ample time to get out.  And in any case, if the car burns out your insurance will buy you a nice new one instead of having the damaged one fixed, which is nice. 
FYI: most fires are caused by electrical faults.  You can prevent this by ensuring that everything is correctly wired up and having the proper fuses installed.  DO NOT bridge a fuse that keeps blowing.  It's not the fuse that's at fault.  Keep a bucket of sand in your garage (or wherever you park your car).  It should suffice.