Thank you for showing these ingame pictures!
The improved normalmap is better!
I have been looking at some pictures on this page, and I want to ask you what time period you are aiming for?
It seems that in the early years the roof were light grey, and squares with a thin yellow edge were placed along the train (see the top picture here).
Later, the squares were removed, and the roof looks way darker (like these pictures).
So maybe it could be an idea to make the roof darker.
Also, the handles along the train doors that are now black should be brown, as far as I can see at the pictures.
I have a few improvements below, that could be added to the mesh on the front of the train.
At the red circle, there seems to be a cable outlet on many pictures. Don't know what it was for.
At the orange circle there is the hinge for the door. This is quite big, and could be added to the mesh.
At the blue circle there is some kind of switch, that could be added to the mesh, or made on the normalmap.
Hope you can use my feedback, because I really like your work!