Regardless of any other technical obstacles, including that there's no such thing as a color VFD (at least according to Hugo), how would you map the colors? The current display has a total of four colors, one of which is black. How do you plan to make decisions about what color should go where? I would conjecture that this is an impossible task. To prove my point, grab one of the logos on riocar.org and try to modify it so that multiple colors look good. Keep in mind that you have to map one color to one other color. It's no fair to decide that this light gray over here should be pink and that light gray over there should be blue, as there's no way for your automatic display interceptor to make the same assumptions.