On a related note, I find that in my 2018 CX-9 Signature, I can get almost 31 MPG on the highway if I follow the stated speed limit (+2). I was a little low on gas and wanted to make it cross the state line and decided to go the speed limit. At times this was 55 (so I went 57) and some times this was 65 (which I went). On my computer, I achieved close to 31 MPG for the ~100 mile trip. Did that the next day again just to see.