Still hoping that this is a test mule for the driveline/engine, but after seeing that the rear bumper isn't hacked up for the dual exhaust (has proper mouldings for two exits), I have my doubt =/
Then again, if they were designing a new chassis for the WRX/STI, then you would expect to see that chassis being tested as well.
Maybe there is still some hope for us!
(edit: does the current Impreza have two outlets as well? If so that could explain the bumper not being hacked up.)
Whatever those wheels are, they are horrible.