[f5fstop]

I can say that my average of 18+ for highway driving from MI to TN in Sept, consisted of highway speeds around 75 from MI to TN, and in TN at 80 mph.
Almost the entire trip was set with the cruise on. From MI to KY is primarily flat, from Louisville KY, to Elizabeth Town KY, is hilly, from Elizabeth KY to TN border is primarily flat with a few rolling hills.
From the TN border Northern Nashville is flat with a long decline at Ridge Top. From Northern Nashville to Centerville, is hilly.
Trip home produced almost the same identical mileages.
This was on a new engine, not even broke in, temps were anywhere from the 60s to the 80s.