Ditto, I'm back to running 93 E10 and my city mileage looks very close to the same. Since it's 40 cents per gallon cheaper, and allows my car to run better, it's a no brainer to run the cheaper/higher octane fuel.
2014 Mustang GT custom ordered to replace the GT500: Sterling Gray, NAV, Recaros, Brembos, Glass Roof, back up camera, 6 speed auto, loaded
2012 Focus Titanium - 18" wheels with handling package
2009 GT500 Shelby (700 rwhp) - sold