I had a 2013 genesis coupe and i NEVER saw MPG over 22mpg with premium, regardless if i drove conservatively and i drove about 50/50 highway/city for the 6 months i had the car. I would stay around 18-20 at best with most conservative driving (it was an automatic) on the 3.8 V6. Then again i didn't buy the car for the MPG so i really didn't care haha.
In hyundais defense, the hyundai dealerships where i'm from are by far the best service/customer support people i have ever met in terms of a dealership. they treated me on time everytime, and with straight to the point here's your stuff answers. Anytime they didn't have loaners available during my service appointments they would let me pick a car off their lots. I'm sure the new gas compensation handouts are nothing but the same quality of service. I WISH my nissan dealer was that good