A ranger told me that he watched a guy bump a bull with his big pick up truck. That bull turned and pushed the truck about 70 yards and really wrecked the front end. The bull was not amused.
Came nose-to-nose with a cow moose once while driving my pickup down a logging road. I suspect that there was a calf somewhere around, because she wasn't going to let me by. So there we sat.
Eventually, she got out of the way, but it took awhile. Wasn't much I could do; she was as big as the truck I was in.