I bought a new Sonata a couple of months ago and finally got to take a decent length road trip last week. With another couple we visited Gettysburg, PA and racked up 1013 miles.
I average 29 mpg with mostly highway driving. I could have done better, but traffic as moving 75 to 80 and that costs a couple of mpg's.
With four adults and a couple of suitcases the 2.0 turbo was really nice on the hills. Power was smooth and readily available when wanted. The car handles well and the ride was smooth. On the way home we went by Washington's Crossing State Park and then Bowman's Hill tower. The road up to the tower is slow but steep. Never heard or felt any struggle at all. XM radio made the trip commercial free too.
I have a couple more trips line up including a 5000 mile jaunt next year. I'm looking forward to them driving the Sonata.