I have 1600 miles on 2011 Sonata Hybrid and have averaged 31 mpg over mostly highway driving to and from work 90 mile round trip which is 80% highway with light traffic and very few traffic lights.
Performance between 20-35 mph is sluggish, and engine clearly overrevs in that range. Bluetooth connection with my Samsung Galaxy Edge Droid does not work.
You can establish a temporary connection which I did when I test drove the vehicle, but it does not hold.
Streaming audio almost never works due to bluetooth phone issues.
Sunroof rattles at highway speed.
Front windshield fogs up on outside all the time from bottom to about 12".
I prefer my 2004 Prius with 189K miles & 45mpg.
Comfortable ride and nice interior.
Nice sound system.
Upgrade the bluetooth system to 2011 world class software standards.
I should not have to go back to a 2009 phone to get bluetooth compatability.
They advertised this car as being world class high technology.
Gas mileage claims are rediculous.
I am very soft on the pedal and have attempted to maximize fuel economy with very disappointing results.
31 mpg is nothing to brag about for $31,850 MSRP.
I think with what you are experiencing you should take it to a dealer. Something is not right. My car works fine so either you got a lemon or??? I average 36 in mixed driving and have gotten 43 in highway only driving. Sorry your car is treating you this way :(