I tested it again today, drove 80+ miles for a shopping trip, did about half at the speed limit of 60mph on the back roads, and on the way home I did about 75mph on the Interstate, filled up when I got back to town, and got a new record high (for my usually heavy foot) 38 mpg. The trip consisted of a couple big hills but mostly level travel. I have about 3600 miles on my Cube now.