I haven't had a chance to do a good second fillup, so can't say what I'm getting yet, but I think it's high 30s to low 40s.
Today I took a long drive, including in an area where it is nearly flat for a few miles. (Hard to find any area like that around here.) The ScanGauge is hooked up and running, but I can't trust the MPG numbers yet as I haven't been able to calibrate it with a fillup. So,
these numbers are best used as comparative, not absolute. The ScanGauge has an averaging mode that can be reset at any speed. Give it a few minutes at a steady speed and level surface, and the numbers are quite accurate. I ran for a few minutes at each of the following speeds, resetting for each one, and came up with these numbers:
40 MPH**-52 MPG
50 MPH**-51 MPG
60 MPH**-45 MPG
70 MPH**-38 MPG
As most of you probably already know, aerodynamic drag doesn't count for much at low speeds, but is increasingly hard to overcome at higher speeds. Clearly the most efficient speeds are around 40-50 MPH, with about a 10% drop going up to 60 and another approximate 15% from 60 to 70.