Apparently, Tom Hanks (you know, the movie star) and his brother were tooling around the West Utah Desert in said Bus when they ran out of gas, and Mr. Tow was called upon for help. So, see, now I'm going to have to up my Netflix rating on any movie involving Mr. Hanks. If he drives a Bus, he must be a better actor than I've ever given him credit for (not that I've been especially stingy with credit for that guy anyway).
You can even see a clip on Vimeo (conveniently embedded here) of Mr. Hanks telling the story on the David Letterman Show: