Okay, I'm going to get graphic here, so squeamish people should move beyond this post. You have been warned...
It looks like a direct hit of flying entrails. The stomach piece is on the passenger side, the handle and the seat are from the passenger side, no question. Look at the rear passenger side window in the sixth shot down, more pieces, possibly intestine, but could be a stomach connector. Cows have multiple stomachs. Shot 5 has some hanging flesh and blood splatter on the window frame. Notice also that mixed in with the green semi-digested stuff, there is blades of grass.
Keep in mind that if the cow was hit by another vehicle, most of the blood would be on the other car (or truck), and the parts that hit this car have most likely already separated from the animal in a pink mist. I am guessing that the part that was still semi-intact with fur still on it hit the lower part and the les intact parts hit the window, shattering it and filling the car with the junk.
That's my take on it anyway. I used to work with a PI while I was in high school, so I rely on some of the investigative techniques from then. It may be a smaller animal, say a goat, but nothing smaller than a goat. Way too much semi-digested stuff to be smaller.
Okay now, anyone for guacamole?
Hey, were'd everyone go??? hehe