An image search for car shade, folding garage, and car canopy yields a few solutions in the right direction, but not completely on track.
They show you "the ultimate inflatable car shield", folding car shades for parking lots, a folding shade that must be attached to your car's roof, a gigantic tent
that completely covers the car, and an awning that extends out from the car's roof.
This idea is about a thin, lightweight folding gazebo with four legs slightly inside and under the roof. One of the legs is held by one of your car's doors, and the other legs stabilize it from the outside.
That's it. Simple, and only half thought through. What problems will I encounter, besides finding out that it's already baked or that there is something better?