Remembering I have the 6... This morning I hit the interstate and set the cruise at 65.. nice and flat...... after 14 miles it was right at 38.5 mpg and may have been a little higher accept for the five overpasses I had to climb... the a/c was off... and hour later when I got back into the car it had gotten 10 degrees hotter and I had to use the a/c.. same stretch back same speed down to 34 mpg... If I go across the state which I will the max speed all the way is 60 on all the state roads.. I figure if I actually go 60 I will get 40 mpg.... no hills to worry about.... there are some four bangers out there not getting that... just an update.... I am sure the 8 speed in the 15 is making the difference....