Amazon has the XBox One and PS4 versions available for pre-order however found nothing for the Windows version of the game.
"It is scheduled to be released on 17 March 2015 in the US and 20 March 2015 in Europe[2] for Microsoft Windows, PlayStation 4, and Xbox One" - http://en.wikipedia.org/wiki/Project_CARS
"It is scheduled to be released on 17 March 2015 in the US and 20 March 2015 in Europe[2] for Microsoft Windows, PlayStation 4, and Xbox One" - http://en.wikipedia.org/wiki/Project_CARS