The Chrysler Pacifica they made around the same time as the Crossfire, had wheels that visually looked almost the same as the Crossfire wheels. And at least some of them did not use a center cover for the wheel on the earlier models.

It was a joint effort of Chrysler and Mercedes, maybe the parts came from the Mercedes parts bin, and those nuts are better looking and happen to also fit the Crossfire.

It probably won't be the case, since the Pacifica was built in Canada, and I realize they are not identical wheels. But maybe you can keep an eye out for some Pacifica's to get a visual idea of what your wheels would look like with nicer lug nuts, or find nuts that look like those.