Well reviewing some of the data from the Vegas trip, I am somewhat surprised.
P&G with EOC at freeway speeds (55-70) did not net any significant returns (48.1 mpg), this could be due to the fact of wind resistance and the engine revving to 2500-2700. On the return trip I tried to keep a constant 60-65 mph with only two memorable EOCs through the Cajon pass and netted (54.2 mpg). While this isn't entirely conclusive because both tanks had a week of my school route on them so there could have been a number of mitigating factors at play. But it would seem if driving on the freeway you're far better off just going a constant 55.
However, to be fair when I first got the car I did a couple of trips from Northern CA (San Mateo) to Southern CA (Temecula) and netted something like 39-41mpg going a constant 70 with 40psi in the tires.
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