Why did the car only fail to start in front of the ice cream shop? Surely there are more occasions where you turn off the engine and turn it back on again within a short time?
Because the story is fiction. There are so many variables that would change the amount of time the engine is stopped: where you parked, how long the line at the register is, whether you had exact change or not. Also the ambient temperature would change both the likelihood and duration of vapor lock.
Yes. There are so many details in the story that are unbelievable. I will possibly believe that there was some original true story with some subset of these circumstanced but it got rearranged and exaggerated for effect.
I will never believe that GM sent an engineer to troubleshoot this problem. Maybe in a small town a local dealer's mechanic spent some time troubleshooting but he probably figured out it was based on the short shut off time. Then he speculated that it took less time to get Vanilla than the other flavors? I doubt that is true - most likely it was random. It is amazing how often a random sequence will have an extended sequence that our brains won't believe is random.
Not sure I even believe there was any genuine observation of correlation from the owner. These type of apocryphal technical support stories are almost always formed backward from a problem and someone tries to think of the most insane way it could have manifested. But people love to believe them.
