I have a full 100 miles (yes, one hundred) on my 2013. And with incorporating the idle time at the plant and dealership to prep the car (I didn't reset the MPG when I took delivery), winter gas blend, and the fact that I've only driven city, I'm shocked that I am only getting 24 MPG!
In all seriousness, I wouldn't be too worried about the 2013 fuel economy right now. Many people are still within the break-in period, winter gas, colder temps, etc. Around this time next year I think you would see the average 2013 MPG up a good big higher, probably very in line with the 2012 MPG.