Take a look at the Technical Manual, the section on Data Cards and Codes, in the subsection labeled Paint Codes. There is a highlighted link called "Rocker Panel Color" that will take you to a 2011 thread discussion of rocker panel colors, in which it seemed to me that it was pretty much the concensus that the rocker panel colors were Dark Grey (Dunkelgrau). I recently painted mine Dunkelgrau (DB164), the same color as inside the trunk, and they look perfect. Where they are located, down low and slanting back into the "tuck under" area of the car, they look black anyway. To each his own!
Tom Kizer