I just went out and took a good look at the sill tread in my CMC (realizing, of course, that CMC often went out of their way to use cheap stuff), but it sure looks a lot to me like kitchen or bath under-counter, toe-kick baseboard, like the stuff in the flooring dept. of Lowe's and Home Depot. If not that, then rubber stair tread material.
Maybe Dr. Clock has different ideas, but if it was trimmed/fitted right, no one could tell what it was meant for, other than a car. I think it's also available in a few colors, not just black.