I think you are still wrong, but at least you pointed out that it would have to be absolutely perfect conditions (extremely rare in the real world) and could not, by ANY reasonable person, be though of as normal driving conditions....
Several people here have said my measured results of 17.5 at 75mph on flat ground are abnormally low and this 20mpg at 75mph is some how closer to normal. Does that seem to be a valid conclusion to you?
I should point out that the Highway and Highspeed portion of the EPA test tops out at 21mpg and has an average test speed of 48.4mph. The Highway speed never exceeds 60mph....