When I drive at those speeds my FE trip indicator (based on reseting the nav screen) shows I get about 32 - 37 MPG depending on the winds.

I can also drive 65 miles per hour with a stiff head wind and get those same numbers, so there is no real magic 8 ball that can tell you what mileage you will get.

It is higly dependent on the grades you travel 9lots of up and down or mostly flat), speeds you travel, number of stops, winds, rain, etc...

Just too many factors to be able to tell you what mileage you should expect.

But, if I had to put a number on it I would say 35 MPG.