I have a FFF 3D printer, and have made quite a few parts for various cars. --I print mostly in ABS.
I've printed some wheel center caps, but in general, those are tough. THat is, plastic is not so great as a spring. Notice that even injection molded center caps often have a steel hoop to keep the 'fingers' spread open. With printed parts, that situation is worse -anisotropic nature of fused layers, makes the part have a grain, like wood. (tough to get preferential grain direction, for those fingers)
As others have said, it's mostly a prototype tool. But, there are times where the 'grain' doesn't matter.
Among other things, I've made a
911 steering wheel bushing, and even these silly little (hard to find) fuel-line clips...
OE broken, on the lower right.
installed:
That was done with a .25mm tip.
I did model up a tail light housing, years ago. Clearly haven't done much with that. :-/