Your tires will have a big effect on these figures as well.
I had OEM tires on when I got my 05. 37k miles. They were P265/70 16's.
I was getting 17+ with everyday driving, and 20+ on the highway trips. Very nice.
Now, I am using Goodyear Silent Armors, LT265/75 16's. These are the larger tire size, and an All Terain style of tire.
Large difference. Now I am getting 15+ everday driving, and around 17+ on the highway. I love these tires anyways.