In general, no. Most concept cars aren't even functional beyond being able to just roll. They're usually one offs as well, so if they sell their concept car what are they going to use as the basis of doing further work off that design if they wanted to?
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.