I would pretty much doubt it was a car factory ornament, but there were several aftermarket options from about the 1920s on. The twenties and the sixties were pretty open about stuff like that, but it was probably not "main stream" but more like the "hoodlum/free love stream."
I can't say what the Lady is from, but the cap that it's mounted on is 1928-1929 Model A Ford. You might have better results on the A.A.C.A. site. Might also be aftermarket.
We should probably call it a "Radiator Ornament". Note that it is actually a radiator cap with an Art Nouveau figure attached....... so it's early, didn't attach to any particular hood but could probably fit many various radiators.