KIM KARDASHIAN Back to Black ... Rolls-Royce

Kim Kardashian just kicked her boring, old, white Rolls-Royce to the curb ... for a flashier, black one. Sound familiar?

Source... Kim used to love her Ghost Rolls ride (which runs a cool $250k base price) back when she was with estranged husband Kris Humphries.

But people move on ... and we're told she started singing a different tune when she got with Kanye West ... and chose to go back to black ... as in paint color ... for the car -- and traded it in.

You know what they say -- once you go black ... you never go back.