I don't see why changing a color wouldn't be possible. Then there wouldn't be any custom colored cars.Any chance you could lighten the car up at all?
The grey is far to dark. The W05 is a light silver, with cyan accents and a black shadow on the engine cover. This texture is just a very dark grey.
I don't know if it is not possible, I have never made a car texture, but if it could be fixed that would be great