the thing that makes carbon fiber expensive is the molds, if it goes into mass production i can see it's manufacturing the cars can get pretty cheap, since they already got the aero design so there won't be any changes made after the fact, like with race cars, they make so many changes and each change usually requires a new mold for the carbon fiber, and reducing the number of molds the cheaper it gets, and if they make the molding process automated (unlike race car manufacturing) they can cut costs even more