Thanks for confirming my findings from the weekend where it was $2.09 at Gurnee, IL but 10 miles down the road past North Chicago, IL it was $2.24. Insane. I also discovered that some Milwaukee residents drive down to Chicago and fill up with the "un-reformulated" gas which they say gets them about 7-8 mpg more from their Prius than the gas around Milwaukee. Maybe that is the big difference in prices - some have winter gas and some have summer gas and others have a mix somehow.

--> Averaged 685 miles/week and 49.0 mpg in first year (35.7k miles from Aug 7, 2006 to Aug 7, 2007)