I just went on a 2500 mile road trip with our 06 Sonata LX. We went from central Fl. to Philly. With stops in D.C. and Charleston S.C.. I averaged 27 mpg with a average speed of 68 mph. We drove about 80 mph on the interstate. In South Carolina the outside temp was 101 and the A/C worked perfect, the wife had a blanket in the back seat so she could sleep. (The windows are tinted though. (Matt)) My only complaint is that the car was like a young horse, we couldn't keep'er slowed down. Thank God for cruise control. My wife does not like cruise control, I woke up to see 100 on the speedo, not to mention the few 90s I saw between naps. She said she did not know she was going that fast and she was trying to stay at 80. The 1800 or so wma's on the 6 cd player kept us listening to "our" music the whole trip. I would give the car a 9.5 on long trips. It would be a 10 if I could slow it down.
Rob