Years ago I was driving home at night after a movie. I had just hit the outskirts of town where the streetlights and such had ended when all of a sudden something ran out from the side of the road and stopped right in front of me. I hit the brakes and stopped within a foot of a young woman who had crouched down with her hands over her eyes.
When she looked up she started screaming at me: "Why didn't you hit me!? Why didn't you hit me!?" I looked at her -- she was crying, and her face was black and blue.
I spoke calmly to her and managed to convince her to let me take her to the hospital (probably a risky move in hindsight). "I'm drunk and stoned" she said; she wouldn't let me take her to the cops. Claimed her boyfriends sister beat the hell out of her, but I suspect it was the boyfriend.
In any case, I won't bore you with the rest of the details. Bottom line from that experience is that I don't skimp on tires when I buy them (you use them for stopping too), or brakes. Having a "third" eye in a car looking out for you and for other people can't be bad.