The 280mph ludicrous speed demon of a car that is the Koenigsegg One:1 is up for sale from its manufacturer. The exact car that is for sale is the development car from the Swedish outfit.
The famous One:1 has active aerodynamics and gps suspension control. If you are interested in dropping $6million and some more, you should talk to these guys.
Development was done and the company is moving onto the project under the name the Regera.