Ever since my 63 impala caught on fire from a Nick in a wire and caught everything under the hood on fire... I put the fire out with my shirt, and than had to go to work with a burnt up shirt... Made for a quite interesting day... I did get the fire out before it burnt the car down, but it did cause enough damage that it wasn't worth fixing... Since I have been carrying one (keep a large one with the plastic shroud in my truck in corner of the bed on drivers side) I have stopped 2 fires from getting out of hand on other peoples vehicles.
I have them in my COUPE, BA*****T, HOUSE, AND SHOP, DAILY DRIVER AS WELL. Just me! I am paranoid I guess ! But Safe for the most part.
I found an old chrome one on e-pay a few years back. Had it serviced and charged (certified) and added a magnetic base. I stick it in whatever car I am driving that weekend along with the detail bag, the harmon-kardon jump box, tool bag and flask.
The Halon was demonstrated to me at a car show somewhere I don't remember where but it won't damage paint. Although that really is a small concern compared to a car fire with people involved. Yes I too have an extinguishers on every wall of the shop and one in the kitchen. Paranoid, nope fire travels way faster than my rear end can run! Joe
When my '61 caught fire (float stuck), the dry chemical extinguisher did far more damage than the fire. Halon and Halotron is all I carry now.
i don't think interior temp is a problem----all commercial trucks are required to have one on board. You can always keep it in the trunk/ out of sunlight if you're worried about it.
When I lived in Tuscon, AZ for 10 years I always carried one in Both My Cars and I still have one in the Merc in the Front Seat and one in the Linc Just my 3.5 cents or when the Cows come Home