I think Phil means more integral things such as the lighting, shadows, reflections and the handling of alpha channels etc... which IMO need a major upgrade.
If this is the case, I think the graphics engine remains largely unchanged. There were a couple of shots showing tree shadows but I think they were actually built into the textures for the section of road they covered.
The new road vehicles have working headlights but this is nothing new to TRS. In all honesty I haven't seen TC bringing anything new to TRS yet.
Cheers