I didn't care for all the white on my 2016 Soul EV so took the plunge and painted the white plastic covers a nice satin black.
This was a bit of work:
Removing each wheel (twice if you don't have 4 jacks to hold the car up).
Removing the covers (15 screws per wheel).
Cleaning them thoroughly with dish soap and some de-greaser.
Scuffing them up a bit with a brillo pad so the new paint would adhere well.
Apply 3 coats of satin black spray paint and let dry overnight.
I think they turned out fantastic and am much happier with the overall look of the car now. They really tie in with the black wrap on the roof and mirrors, and other black accents on the car.