studencio, from my understanding, "De qué color es...?" is used to ask about the color of an object. It puts the focus on the object for which you want to know the color of. Whereas, "Qué color es... ?" is used to ask for the name of a color so if you are questioning whether the glasses are blue, green, or turquoise for example because you are unsure of how you would name the color. The focus of the latter (not using "de") is on the color itself and has nothing to do with the object the color is on. Hopefully my explanation hasn't just made you more confused!
Yes, but it sounds really archaic. It is how Shakespeare would ask your car's color. :-) "Good sir, of what color is thy car?" It is has been my observation that many Spanish grammatical structures correspond with Old English ways of speaking. For example, "A mi me gusta..." is like "As for me, I like..." This is okay in Theater class but it isn't how we speak in Modern English. However, understanding how Old English works has given me a better handle on Spanish phrases. Hope this helps.
@StuckinSan, prompted the discovery of this well-written article :))
Car's don't have attributes in the possessive sense in English. Objects tend TO BE an attribute. "The car IS red, old, slow, junky, broken down, etc." You can use possessive when speaking of car parts but not attributes. "The car has a V6 engine," "The car has four doors" (alternatively, you can say the car is a four-door), "The car has an engine problem." So we wouldn't say "My car has red" or ask "What color does your car have?"