I have a rev up on 17's (Yeah, I know, I was pissed when I found out too, but the deal was too good to pass up) I get 15-17 city depending on how I drive. Gas is so much I am normally in 6th gear by 40mph and it's going up a little.

100% highway the best I've ever done was 24.5mpg but on a trip from jacksonville to Madison, Alabama...average speed 85mph with an hour or two at 95mph (partly down hill), and yes I have the ticket to prove it. The highway mpg goes down really really fast once you exceed about 78mph. Keep it on cruise control at 70-75 and you might be able to see 26mpg.

 

I've managed 26 out of my 5AT Sedan. But it was cruise set 70-75, 100% highway, no A/C
Most of the time it's more like 22-23