I own a 2012 Sonota Hybrid Limited. I am currently getting 24mpg in city driving. I have done all of the service upgrades recommended by this forum and it's readers. I met with a field rep today to discuss the poor mileage. He told me as long as I get 23mpg or better Hyundai won't do anything for me. I have spent numerous hours on the phone with Hyundai and several trips to dealerships without any effect. Sorry, that is not good enough...this is the third Hyundai we have purchased since 2010. One would think Hyundai would value me as a customer. Apparently not. Too bad....I like the car other than the mileage. Hyundai does not stand by their customers based on my experience. Won't buy again.
Mileage like a Prius...Better sound insulation for road noise.
I can't say for certain without seeing you drive it, but I am willing to bet you are driving it like a regular car and not utilizing any of the hybrid drive techniques. If you drive a hybrid like a regular car you will get horrible mileage. I recommend you look into the multiple hybrid forums online or get with someone who gets above 40 mpgs in their sonata. For the record, I have gotten 70 mpgs over a 30 mile span and I never dip below 43 mpgs unless its below 50 degrees outside.