I've only done a purely highway tank once, and it was when the car had ~800 miles on it. I'm now up to 2,450 miles and the mileage seems like it may have improved a bit. I've used 93 octane from day one (I don't think it does jack for mileage, but use it because I believe it improves drivability and performance on these cars.).
-Varied, with some very steep hills thrown in for part of the trip.
-38 psi/36 psi F/R, IIRC
2012 Ford Focus SE, ╠╬╝, Sport Package, Ingot Silver. 1993 Volkswagen Fox. Formerly: 2005 Focus ZX3 SE, ╠╬╝, Pitch Black, SVT suspension.