i was thinking that but
I filled up in Pittsburgh on the way out. Filled up in Carlisle before I left and refilled in Pittsburgh. So essentially I got 19 mpg in the mountains but in the flat and downhill in Ohio, I got 17.
Then filled up in Cincinnati otw back and it had dropped to the 17.0z
The 15.5 I know came from hitting rush hour traffic in columbus yesterday but I hit zero traffic today.