Mark,
Your regular commute mpg sounds similar to mine, though our route conditions are different. Mine is 40 miles each way, town starts and finishes (traffic light variables on both ends), in the middle fairly light traffic moving 55-65 with occasional morning stops for school bus loading and a couple of 45 miles per hour zones for a mile or two. Temps have been 40s at night with days 50-60 for a few weeks. I've been seeing 32-34 mpg pretty regularly, almost always +2 mpg on the return trip because of elevation (though a strong southerly can quash the downhill advantage).

Good to hear about your 39 and 37 experience, since it suggests the HAH can beat the lower 30s. I really didn't (and don't) know what to make of the 40.1 mpg I got on a 50+ mile trip yesterday, not a regular route so I'm not sure of the variables (elevation? tailwind?), but the number sure got my attention. Very interested in hearing updates on your commute numbers. Thanks for sharing them.
Lewis