I may have misinterpreted what you are trying to achieve with your mod, i was purely talking about game balance. I agree with you about commuter train and standees, but as much as i would like a Z8100 with it's full compliment of passengers i think it's a bit over the top for the game (~570 passengers for a single unit using your calculation rule).
About the tga to dds conversion, i would like to know what you are using. While i can save DXT5 files (for albedo opacity) and DXT1 files for dirt and material using paint.net, i haven't found how to convert normal map to the proper 3Dc format. And on the contrary of what you seems to believe, i have installed everything that is listed in the lexicon article, but the nvidia texture tools is the only one i could get to work properly. And it seems i'm not the only one as @OlaHaldor say in is steam guide that i quote :
I have tested three different converters, but only one of them could do the job properly. By properly, I mean: Transport Fever did not crash.
This plugin require Photoshop.
Get the nVidia Texture Tools for Adobe Photoshop here
So, i definitly may have missed something here, so i you have a better solution than using photoshop, i will be very interested in it