Blink,
I'll tell you what I did... That changed the color at night...
If you open the model in MED and go into the skin settings dialog...
"Edit" / "Manage Skins"
Highlight the skin that you wan to revise...
Click on "Skin Settings"
You will see that I enabled the "Material Set Up" toggle... of each skin...
If you click on the "Diffuse" & Ambiient" buttons, you will see that I changed the colors from pure white to two different greys...
I suggest that you play with these settings and run the project to see what happens...
These two settings really help with realism of shadows and color depth...
If you want it back to the way you had it... simply turn off the "Material Setup" toggle button...

Also... under map properties in WED, I wonder what color you have the sun and fog colors????

I will download the project, right now, from the link you provided...
I will get back to you very soon with comments...