Should Ford have used the word farther instead of further for promotional displays at the Women's World Curling Championships? They definitely needn't have capitalized the F-word in their tagline, and missed out sentence final punctuation as well.
Word-choice arguments, as you might imagine, can go full circle. For starters, an Oxford Dictionaries' grammar and usage resource made no distinctions, when talking about distance; it argued, "[B]oth are equally correct."
But isn't that like arguing two stones are equally close to the center of the house? If you watched the end of semi-final play between Japan and Russia yesterday (relative time), you may recall that the Japanese team quickly conceded a second point for closeness in the house on the 10th end, and won outright with two points of their own in the 11th.
Thus, perhaps, the Oxford Dictionaries' site conceded, "... [except] in various abstract and metaphorical contexts" (http://www.oxforddictionaries.com/words/farther-or-further).
Cambridge Dictionaries Online's argument included similar nuances: "There is no difference in meaning between them," when talking about distance. However, "[t]here are some occasions when we can use further[,] but not farther. / We use further before a noun to mean 'extra', 'additional' or 'a higher level'"
The Canadian Oxford Dictionary Online called farther a "var[iant] of further …" (2005, inaccessible after first viewing), but wouldn't reveal the definition of further without a purchase or subscription. The definition of one word isn't much of a sample to preview, eh?
Grammar Girl surmised, "The quick and dirty tip is to use 'farther' for physical distance and 'further' for metaphorical, or figurative, distance. It's easy to remember because 'farther' has the word 'far' in it, and 'far' obviously relates to physical distance" (http://www.quickanddirtytips.com/education/grammar/further-versus-farther).
You don't think Ford marketeers were unsure, do you?