I just saw an ad for the AF 6-49893 Earthen bumper and the earthen part has the speckled look of the SHS/MTH S-Trax.
That shows Lionel had the ability to make the ballast on the Fastrack a little more realistic in coloring but they chose to stay with the plain grey look of the O gauge Fastrack.
Too bad...I prefer the SHS look but it was no longer in production when I did my layout in Fastrack.
Mark