If it where me I would paint the whole car the same color.I been a auto body collision tech for 26 years and if the top surfaces of the car is faded and the body shop cares about the work they do they will have to blend the color to the header panel and fenders when painting the hood and clear all panels.When painting the roof they will have to blend color into the quarter panels and clear the roof and whole quarter panels too.When painting the trunk lid they are going to have to blend color to the quarter panels and paint the filler between the trunk lid and back window also and clear all panels,some shops will panel paint but there is almost always a difference in color and texture. The roof can't be panel painted because there is no break off point so they will have to blend the clear and melt it into the quarters,usually by the side window or at the first body line on the quarter.Over time the blended clear will break down from the heat of the sun.The reason for blending out the color is so you don't see any difference in color from panel to panel,so with that being said the only panels left to paint is the doors,bumper fillers,quarter extentions and rear spoiler, if you have one.This also gives you a reason to take care of any dents and dings you might have.Also if the faded surfaces are cracked (checked) they will have to be stripped to bare metal to do it right.Doing it this way will ensure many years of enjoyment with no paint issues,but will cost quite a bit more roughly $3,000-5,000 depending on how much body work needs to be done.Good luck and take your time picking a auto body shop to do the job,remember some care about their work and some care about the money only.If you have any questions feel free to PM me.Thanks,ikle.