I actually noticed some dropping inside the cab when i was cleaning over the weekend. I opened the hood and sure enough the space between the sound dampening material/metal and top metal portion of the hood was filled with cracked acorns. My wife's car and my sports car also had plenty of that under the hood as well, but I hadn't seen it INSIDE the cab! I was shocked when I found droppings inside.
I have a cat, and she catches the mice but won't kill them. She just plays with them.