My Prius C seems to have a 10 mpg advantage over my 2005, Gen 2. ( a ball park figure ) What is your read?
I think you are pretty much on the money. In our 2008 Prius I average 4.7l/100km = 50 MPG (US), in our 2012 Prius c I average 4.1l/100km = 57.4 MPG (US). It's possible that our 2008 Prius is a little more economical than your 2005.