Actually, the more I learn, the more I am convinced that trying to isolate a single variable for testing is beyond my patience. The engine in this civic (R18a) has a vtec that is kinda backwards from what we are used to thinking. In short, between 1000 and 3500 rpm, low cams may be engaged, IF the conditions are right for fuel economy. See
http://asia.vtec.net/Engines/RiVTEC/ for lots of details. Cool stuff.
Between that, the CVT and ECON mode, the car is doing a ton of mpg optimization in real time. This car is made for MPG. If you want a 'performance' Civic, you get the Si, with traditional vtec.