The 2012 Prius builds on the previous Prius engineering. To find out what the new items are for 2012, download the New Car Features manuals from
http://techinfo.toyota.com/ There is a nominal $10 fee for a day's unlimited downloading. You'll also want the 2010 NCF manual because that details the changes made to the third generation Prius.
For a detailed description of how the Prius works, select "Understanding your Prius" from here:
http://www.ecrostech.com/prius/original/PriusFrames.htm Although only the 2001 Prius is covered, the basic principles remain the same.