Regarding the black and white discussion - it has to do with additive and subtractive color. If color is viewed through a light source (shining different colored lights into the same area) then all colors combined equals white (additive). If color is viewed through a material that reflects light (such as paint or anything else that is not a light source) then all colors combined equals black (subtractive). With additive (light) you begin with nothing (blackness) and as you add more colored lights to it, it gets lighter until you reach white. With subtractive (paint) you begin with nothing (whiteness) and as you add more colored paints to it, it gets darker until you reach black. So on a car, black is the sum of all colors and white is completely devoid of color - technically. (Sorry, I'm a graphic designer and had a few too many color theory classes drilled into my head in college - I'm a little obsessive about that stuff).

For another fun discussion in color theory, you'll find that shadows cast the complementary color of their light source. (Red lights cast green shadows, etc.) So, since the sun is actually a yellow-orangeish light, most shadows are actually bluish-purple. The only time you really see a black shadow is if you have pure white light. - I know, nobody cares, but I think it's rather fascinating.