I took my Cruze on a 392 mile round trip. This trip is almost entirely highway and about 2/3 of it is 65 MPH speed limit. I generally run 65 MPH in a 55 speed limit and 73 in a 65. Much of the drive was with cruise control. The average speed on the DIC was 57.2, indicated MPG was 39.8 and calculated was 39.6. I meant to put the tires up to 40 PSI, but forgot - they were 37 on the DIC.
It was great to do the trip on 1 tank of gas. This is a drive that I make often. My former Jeep Wrangler would get between 15 and 16 MPG on this trip driven the same way and use 2 full tanks of gas.