Hi Markan:
___If you own the stick, to achieve anything near 3.75 L/100 Km, it would be essential that you use both intermediate and advanced techniques unfortunately. If Toyota would have ran a tall 4th and 5th (they really should have as the motor is plenty strong for it), this would not have been the case given the 2.4L motor in the Camry can achieve essentially the same FE as the Corolla at steady state highway without doing anything but driving.
___There is some break in but it will not be worth but maybe 1 to 2 mpg. The break in comes from you learning to drive your Corolla to its potential which you will learn quickly enough
___Good Luck
___Wayne