Also, the concept cars that are functional - does anyone remeber the v12 chrysler from 'THE ISLAND' - are show pieces that can find value later. Like the use in a movie. Theres no justification for selling an item that would bring value to the company. Other show concepts of mention are -
Dodge from 'the wraith' 80's movie
Audi from 'I robot'
Lexus from 'minority report'.
Shelby from Gone in 60 seconds - incidently now a production vehicle
All of these where 'somewhat' completed (the dodge, chrysler, and ford where functional) and they all got recognition for the company that designed.