Mine is a Kidde 2 pound auto model, dry chemical, type BC. I now have 2 of them ($12 each). This one:
http://www.kidde.com/utcfs/ws-384/Assets/466310%20-%20Auto%20Fire%20Extingui.pdfA lot of my friends are firefighters, and I have firefighting experience from the military. The main thing to know in a vehicle fire is to get all the people out, leave everything else. Nothing in your car is worth your life.
Also, if you don't have an extinguisher, leave the hood down if the fire is under the hood. Opening the hood will only make the fire worse.
And make sure if you do have an extinguisher, it's where you can get to it quickly when you need it. And that you know how to use it. Familiarize yourself with your specific model, as there are lots of different types that operate differently.
I wouldn't carry anything less than a 2 pounder. The spray can small ones are not really going to work long enough for a vehicle fire.
And I'd say the car is salvageable, but the wiring harness and other plastic parts would cost a good bit. He said he was considering it totaled. The first thing he did was get the 2 puppies that were in a kennel carrier out of the car, that says a lot about the guy's priorities being in the right place to me.