^^^ yeah, agree, hard to believe the 40 mpg.
It's tough not to be skeptical since one can expect a 5-10% increase but not 35%.
By any chance, was your 27.5 mile a round trip on the same route? For instance, there could have been a slight downward grade as well as a backwind in the direction the tests were run favoring the the results, but if you went back on the same route, it would average out.
BTW, thanks for sharing and if anything, some of us will test this out over the next few days - I will.