I have to many logging trucks and 18 wheelers up here tossing rocks at me to risk an outside the vehicle rack. To many bugs too. That and I hit birds alot. I had a Great Blue Heron a few years back, that cleared hood, windheild and I assume the roof of my car by a small enough amount it would have taken out both of the rods in the photo before it ever made it to the roof. It came up over a bridge and I'm sure it was the air I was pushing that made me miss it. It followed the contour of the car. It was close enough to see the wrinkles in his little poop cutter.
I found it dead a couple of days later in the same exact spot. Dumb bird did not learn it's lesson with me dusting his feathers for him.