How to even out/scale this material? I have this PBR set up and working, but I'm getting different results on different objects. I have UV unwrapped the objects (using smart unwrap). The texture itself is working. I have applied rotation and scale. 

Per another thread, I added a UV Map node fed through a mapping node in order to scale, but it is not working. I am wondering if the color node and the mapping nodes need to be mixed somehow?

I tried just scaling the UVs in the UV Editor window, but it seemed to have no effect at all. 

I also realize that the UV map has a specific UV group specified, so I am not sure how I can apply a material like this to multiple objects (perhaps name the UVs all the same?)

You can see on the cab how pronounced the material is, but on other objects it looks very flat and smaller. 

You can look at the blend file here:
https://www.dropbox.com/s/4n7aqyfuik4oy6t/cab.blend?dl=0



UPDATED NODE SETUP
You don't need to specify the Uv channel if there is only one per object, so leave that empty. Also remember to connect your mapping node to the vector input of each of your texture nodes.