Gee wiz this is tragic. People are so unhinged these days. You get so angry you ram a car and start shooting at it? And then that gets the other guy so mad he starts shooting back at your car? This is nuts.
That part isn't nuts. Unless you think letting someone kill you with his car or his gun is just the better part of valor. I suspect fear was more likely his main motivator than anger.
I think the BMW driver, aka dead guy, shot at the other car, the other guy, aka the alive guy, shot at the other driver. Result one wounded car, one dead guy.