I recall one night, my car died right off the traffic circle in Dothan, Alabama.
It turned out to be a broken wire in the distrubutor. (I have a mental block right now and can't think of the part's name) By luck I happened to have a spaare in my trunk.
Right after pulling over, a Dothan city cop stopped and asked if I needed help. I told him I thought I knew what it was but would appreciate it if he stuck around long enough to see. He not only stuck around but helped me fix it and also kept up a very interesting conversation.
In some places he probably would have searched the car (for his own protection), called for back-up, and cuffed me until he made sure I wasn't the Son of Sam killer.