These types of vids, and the screen shots uploaded to the forums, are great places to study to see how these modellers do it. The trick seems to be staging. So many of the assets on the DLS look rather crummy by themselves, but when used in combination with other assets, the same assets turn into amazing shots. Notice that the gravel texture on the ground matches the gravel in the track for a seamless fit. Also notice how few speed-trees are being used. Just enough to draw the eye away from the 2D trees. This vid is pure art, and it reminds me of stage productions for the theater, or good special-effects in films that predate CGI.
(Doesn't hurt that I have a soft-spot for Southern tuxedo diesels.