I didn't get any more info on tuesday since I took the work truck but got some more interesting numbers yesterday on the drive home.
I was listening to an audio-book so decided to use the chapter lengths as my intervals. This time I recorded distances and did not throw out the "short" runs interrupted by towns or construction. I still didn't record anything from the first half hour or when there was other traffic on the road affecting my speed. Cruise control and max A/C.
Here is the raw data recorded from my scangage on each leg:
km/h (average) - l/100km - km traveled
100 12.6 58
114 13.6 92
105 13.3 64
110 11.3 59
100 10.6 57
114 13.8 72
104 11.8 48
110 12.1 30
Combining the new numbers with the old ones I made a bubble chart giving the old numbers a 50km weighting (since I was not so careful about conditions on those numbers)
115 is obviously NOT an efficient speed, but the flat trend between 105 and 110 is interesting.