S3 will be released on 21th Oct 2011 and it will feature upcoming DX11 graphics engine, CFD-based aerodynamics model, advanced algorithms for brake, engine and water temp, dynamic damage model using young-modules physics and many more thrilling features.
I reckon late 2008 for s3 alpha, somewhere around 2009 release.. IF started straight after s2 release, but i dnt think people would want the devs to work straight away