I don't know why everyone says the handheld extinguisher doesn't do any good. My car started running like crap and I could see the flames coming out of the engine lid so I stopped and Troy opened up the engine lid. Rusty ran over with his extinguisher and put it out. There was no sudden flame up because the lid was opened and even the fire extinguisher were in my car and clamps we would have had time to put it out.
Do I think this is the same scenario every time? No. However anecdotal it may be not every engine fire is the same as any other fire. Besides, if my car burned to the ground I'd cash the insurance check and build another one. That's why the car is insured.