I wonder what it says about me that I was super excited to find this.
I suffered through many arguments in high school trying to explain that calling shotgun really was something that required rules. I stuck to the basic, outside and line of sight rules, but love how complex this article gets. I especially enjoy "The Balk" rule.
This rule is applied when you have called Shotgun and are waiting for the doors to be unlocked. If you lift the handle while the doors are being unlocked and therefore cause the Shotgun door to remain locked, then you are "voided" for that ride. At this time Shotgun is available for all of the other passengers to call.
I won't be buying the handbook, but I admire the author's attention to detail.