I am having the same problem you are Bill. It looks like a Fiat, although I think a bit earlier than a 525, but I can't locate those slanted louvers (some Ansaldos have slanted louvers, but the radiator doesn't look right). Since the name of a coachbuilder is required, I'll assume that the unique louvers are a product of the coachbuilder, and call the puzzle car a: 1926 Fiat 512 by Fissore.