If your only geting 13 mpg city, then something is wrong.. Or your flooring it the whole time? Try a different gas station... Also unplug battery(for 30mins) right after you full up with 93 octane, that should help out a bit...
Summer gas is the best gas...
Black 2014 Mustang GT Base
MRT Boss H Pipe, QTP(with wireless), KOOKS Side Pipe, W/O Resonators, FRS QUADS, Pro-Cal Tune
GT500 Valence, MMD Window Pannels Kenwood Excelon DDX9903S
2 Alpine PDX-V9
2 Alpine SBR-S8
Morel Elate 6.5"