I thought of a quantitative test for this best gear choices for the hypermiling debate.
Using a well known stretch of highway, I used canion to compare two back to back (as identical as possible) runs. One using D and N as needed and the other leaving the car in B the whole time. Both runs I used the same efficient (smooth changes and finessed pedals) driving style. Reseting the trip at the base of the on ramp and taking a screen shot at the stop sign at the end of the off ramp. I found the details interesting. The most important data is the Mi/kWh summary achieved for each run.
Using D and N as needed the result was 9.5 Mi/kWH
Using B full time for the run the result was 7.9 Mi/kWh
The bottom line is that D and N as needed resulted in 9.5/7.9 = 120 % the efficiency of the same drive at the same speed under the same conditions in B mode.
On the way home I thought "hey I should have done the test in every drive mode for comparison". I'm curious, so I will go back and compare full time D, E, and B again under the same conditions.