I'm assuming all of the white areas are chipped paint. Chipped paint always has a thin outline on one side depicting depth. Go through and depict depth with the scratches, and paint chips, and it won't look so dirty like a bunch of colors mashed together. Also, get something like FRAPS, stand the model somewhere a bit off from a light source so one side of him is lit well, and the other is a little shadowed. Then record a turn around video of him so we can get a look at the shaders functioning and we can get into some really cool ways to make those scratches and chips and faded paint pop out a bit. Pay attention to that last ref pic, see how the shadowing is mainly on the bottom and right of the chips? Then you can take that shading back out and apply it to the bottom and left in the specular map and it will just pop those chips right out. Then you can alpha mask the actual chipped portion (the yellow area in that last pic) and give it a masked TcGen Env map to it. That way only the chipped off white areas in your model will have a more metallic shine to them. Then you take those white areas, and in the spec map, make them a bit more chrome-ish.That way when the camera is right in front of him, the scratches will be white like you have them, with some depth, and when you rotate it, the scratches and chips will be more metallic looking and the paint chips and such will shaded from the other direction faking the light transfer. Just some ideas to fix the closer shots.