I have to think that over time squirrels must be evolving due to cars. I do see dead ones, but I often see them running across the road, and notably not zigzagging. They still don't seem to have a sense of how close and how fast a car is moving though. I've seen a coyote not only assess the trajectory of my car, but change its mind about crossing the road in front of me once I demonstrated I had no traction in the snow.