i dont have a 2011 stang, but i know back when my six was stock getting a gas mileage tune and k&n cold air intake i increased my city mileage by 7 mpg's went from 19 mpg's to 26 mpg's my freeway increased by about 2 mpg's. though i did drive the car carefully, not gunning it at all and shifting at 2k. even though i got a gas mileage tune i had much better throttle response and better performance as well. sure it would have been better performance if i had gotten an aggressive tune but i settled for better mileage with a moderate performance boost.

 

I don't get miles per gallon I get SMILES PER GALLON