What type of Octane levels (Premium or Regular) are you running?

Do you run the A/C all the time?

Is your driving in city or highway?

Are you an aggressive, moderate, or casual driver (Peddle to the Metal Factor)?

And while break-in does yield some improvements to mileage, typically you will not see a 10 mpg gain happen overnight when you reach a certain mileage milestone (let's say 3K miles).

XFH