If you want MPG ratings like the sticker shows, then you need to drive the vehicle close to the way they did in performing those tests.
http://www.fueleconomy.gov/feg/fe_test_schedules.shtml
Note for the Hwy test, average speed was 48.3 MPH, so they're probably running it around 55 mph.
Also another decent article on Edmunds about rated mpg.
http://www.edmunds.com/fuel-economy/...a-ratings.html