While the vinyl dye I suggested is sprayed on, it DOES permeate the surface and soak in to the core of the plastic. If done properly, you can scratch it all you want with your fingernails, and it won't come off.
I've done multiple dashboards and door panels with it. I even did some computer DVD burners with it, from white to black, or white to blue.
I absolutely love the stuff.
The only real down-side is that it only comes in a few colors.
And I agree...start with white to get a nice bright crisp color.
I dyed a blue dashboard black, and it turned out great. I also dyed a black dashboard blue, and the blue was a few shades darker than what the cap was.
And get this...you can even use the stuff on carpet! You just gotta brush it out afterwards, otherwise the carpet will be stiff, like a wire brush.
I've done multiple headlines with it, too, including the gray one in my van. I dyed it black, and it looks factory.