I don’t think you know what a straw man argument is.
A car represents (for average wages and car prices) a few hundred hours of someone’s life. Would it be reasonable to use deadly force to prevent someone from kidnapping you and holding you prisoner for a week or two?
Someone who chooses to steal a car knows that the owner might catch him and shoot him. If he values his own life so little as to do it anyway, why should anyone else value it more?
“If someone values human life so little, why shouldn’t I lower myself to his level?”
I don’t necessarily even take it to that level. If I knew beforehand that all the carjacker wanted was my vehicle and I could be on my way, then no problem. That’s why I have insurance.
The problem is that if someone comes up on you unexpectedly and jerks you out of your car, you don’t know what his intentions are. He’s obviously desperate, probably unstable, and he might take your car and leave you be or put a bullet in the back of your head as a parting gift.
In that situation, I consider it to be reasonable to use deadly force to protect my car as an extension of me. Of course, the devil is in the details, but it’s not just a car vs. life equation.
I presented an argument involving the imminent death of yourself and others which is not a straw man to the question of when is deadly force justified. I also presented a real case of war/destruction that could not have been dealt without the use of deadly force.
Without the use of force to counter the likes of Hitler or Charlie Manson the end result is the death of others.