I purchased one too. My first new car! Completely love it.
Instead of ordering a 2016, I got a 2015 GT that was still in stock. Black, Premium Package, Performance Package. Got a great deal on it too.
These EPA numbers are more of a "lessons learned" exercise (my opinion). What I've actually seen from driving S550 is considerably better in both city and highway. Then again, I sometimes drive like a grandma.