General Motors built 12 Futurliners for the three-year futurama road show in the early 1940s known as the "Parade of Progress." Nine of them still exist, and one would think that in a world where we can use a carbon molecule to divine the birth date of a dinosaur and have tiny robots sorting out our feng shui on Mars, we could keep track of nine vehicles. Yet according to an article on Hemmings Daily, that's not the case; the nine extant Futurliners have been through so many hands and/or so much part-swapping and neglect that it's, so far, impossible to be certain about the provenance of each.
The Hemmings piece does its best to assign a number to each and recount their histories based on the exhibits they housed for the "Parade of Progress." Nevertheless, at the end of the investigation there are still loose ends, like what happened to the other three and why two of the known models can claim to be the Number 7 Futurliner. Head over to Hemmings to read the fascinating whole story.