I frequently use Testors Clear Parts Cement, 5 minute epoxy or clear paint/Future on items such as this. It depends on the application and the features of the attachment point, and whichever I think I can get attached more cleanly. Some of these adhesives won't hold well if handled often, especially if affixed to polished paint. CA is the best adhesive, but can be messy for such a high visibility application as body badges.
Micro Krystal Clear works as well, and if the part is very small and light and in a spot where it won't get touched (interior, etc), I sometimes use Micro Liquitape.