I'm a little puzzled by this, but here's some real-world data. I had to go on a trip out of town this weekend in my new AWD Cross LE. Due to it being during the break-in period, I didn't use cruise control -which means my speed was constantly wavering between 40 and 65mph with RPMs between 1,000 and 3,000. I exited several times and took back roads with speeds varying between 25 to 45 mph. I made stops every 20 to 40 miles. I wasn't at a steady RPM or speed for more than 30 seconds at a time.
I filled up my tank in Weldon Spring, Missouri, then drove as described to Mount Pleasant, Iowa where I filled up again. The distance between fill-ups was 192 miles, and the tank took 4.9 gallons to fill back up at the second stop. That is 39 mpg! While I won't be driving like that moving forward (I'll be doing mostly highway miles at 70mph+), it was very surprising to see that number.