Is Bell really referring to Vietnam and not WWII at the beginning of Chapter 7 in No Country for Old Men?
Sheriff Bell is referring to the Vietnam War, as he is a veteran, just as Moss is. Bell struggles with the fact that he received a medal for combat action in the war while he still lost his entire squad in the fight. While Bell is perhaps old enough to have fought in World War II, references to Vietnam keep coming up in the story. He does mention how the kids of the modern day are more callous, violent and indifferent than the kids now (the book takes place in 1980). This theme of violent and unpleasant change lasts throughout the book, and the fact that Bell is unprepared for it, and doesn't understand it.
Chigurh does change cars frequently, to throw off both law enforcement and those he is pursuing. Unfortunately this means he kills several people just to obtain their cars. Again, this is the violence that Bell can't understand, and doesn't know how to fight. At the end of Chapter 7, Chigurh drives off in a Barracuda.