It's like a pre-prototype. It's the design for a new car they MIGHT make-- like a preliminary sketch for something you're thinking about painting, or an outline or a rough draft of a story you want to write. If it goes over well, or they decide they really like it, they'll make it-- if nobody likes it, or they find some design flaw, or something like that, it's scrapped.
What is the point of a concept car?