An excellent car render by Rogério Perdiz. The .blend file is available for download!
On the last 4 years, I've been developing an accurate model of an 2006 Opel GT. The entire development was registered on the blenderartists wip topic with the same name.
For me this project continues to be a wip and will try to finish it someday.
I'm releasing it hoping to see some cycles renderings and also to everyone better see the details and learn from my mistakes :)