1-Tire pressures 2-system "break-in".
I just got in from the Honda dealership (hadn't planned on going there for a while as it's too far away, but had to pick up my plates) where I asked about the "break-in period" and also tire pressures for my 2007 Civic Hybrid.
The break-in is several thousand miles for the system to learn my driving style. somehow it then makes adjustments and am told I will see further FE gains.
The Dunlop tires are rated 32 to 44. The service department says
1 - all cars' MPG ratings are with the tests at the tires' upper limit,
2 - you will see longer tire life if the tires are inflated even up to that limit, and
3 - running with tires inflated at the upper limit is SAFE (important to me, esp in wet conditions) though HARD. I'm going to give 40 a try this week.
My trip to the dealership involved Dallas, TX hwy and city mix. Thrilled to see 48 mpg at now 2,500 miles of conservative driving.