I like the story with the older model Citroen. If that old Citroen could make it up the hill in 4th gear, it was a category 4 climb. If it stalled out in fourth but you could get a run at it and climb the hill in 3rd gear, it was a cat 3 climb, and so forth. If the car couldn't make it up the hill in first gear without stalling out, it was HC (above category or, in French, Hors Categorie).