A phrase emphasizing one's availability or openness to a situation. It refers to Mr. Barkis, a character in Charles Dickens' novel David Copperfield, who used the phrase to express his interest in marriage." -- Urban Dictionary
I didn't expect to find Henry Ford quoting Dickens, but that's apparently what he was referring in late 1906 in response to the Packard sales manager's press release concerning six cylinder automobiles. Sales manager Waldron began, "Six-cylinder cars are a fad and much over-rated....... : "
Henry Ford, returning from a hunting trip to the upper peninsula, responded, with his comments carried in national automotive publications as well as major newspapers, "Barkis is willin':"
Ford went on to challenge Packard to a one on one comparison. The Ford Six, at $2800, was a much less expensive powerful, albeit it less finished automobile than the new model Model 30, priced at $4200. In todays dollars, the Ford sold for about $70,000, while the Packard at over $100,000.
I've only found one example where the gauntlet was picked up by a Packard owner, and the results were not well publicized, although the Ford did finish the winner in this instance:
