I think the "hue and saturation" won't work when the texture is too dark or too gray, or bright..
You can try the following:
- create a new layer
- pick a color, color over the existing texture on that new layer
- change the new layer's blend mode to color burn or color dodge
- adjust the new layer's opacity
When you paint over the existing texture on the new layer, make sure not to paint over the head/tail lights and badges and door handles and glass, it'll look bad.
It's a lot less work when you start with a car that already has some color (meaning it isn't gray, black or white) because you can just adjust the hue like you've tried to do here.
Edit: even better, just use burnside1024_c.dds instead, you'll have to re-color the roof to body color, but it's a lot less work. Adjust hue and add some saturation. Make sure to exclude headlights and tail lights when doing this (cut and paste them onto a new layer, merge them when done?)