After searching multiple places and thinking I "almost" had it, I think I may actually have it. G. N. Georgeano's exhaustive Encyclopedia of Motorcars wasn't as much help as I had hoped it would be, but Bev Kimes & Austie Clark's Standard Catalog of American Cars 1805-1942 turned the trick (I think). I'm pretty sure this is a 1917 Detroiter "Six-45" Roadster, built by the Detroiter (some say it was actually Briggs-Detroiter) Motor Car Company of - where else? - Detroit, Michigan USA. But I could, of course, be wrong. Am I?