Both my '11 and my '12 are always 1.0 MPG too optomistic at the end of a tank. So I reset the display each time I fill up, and then whatever the display shows, I just subtract 1.0 and it gives me my exact mileage.
~Lots of modded Jeeps and a Toyota 4Runner~
My favorite quote from the press release.. sad but true: "Chrysler claims its products, especially the Jeeps, can handle all sorts of terrible conditions, churning through muddy swamps, climbing mountains, and crossing rivers. Turns out they cannot even handle a car wash."