I think people are puting too much faith into break in periods. Today's motors require very little break in . You won't even find a section in the owner's manual about it anymore.
Truth be told, EPA estimates are all calculated on a dyno. The dyno offers different resistances to it's rollers to simulate real world conditions.
But everyone's driving habits are different, as are their daily routes. So everyone's real world fuel economy will differ from each other and most certainly from the epa estimates.
Idling, jackrabbit starts from a stop, pedal modulation, excessive braking, terrain, climate and a bunch of other factors play into real world mileage.
For better fuel economy, try to really FOCUS on the way you drive. Overall, this will be the biggest factor to better mileage.