I would have to say the gentlest rate of acceleration while staying out of boost will give you the best mileage. I tried this for a painful and nerve-wracking tank of gas in my legacyGT while watching the instanteneous mpg display. When decelerating, my mpg shot way up and just inching up on the gas while accelerating kept the fluctuation in mpg fairly moderate. I averaged 25.6mpg for the entire tank of gas. I am usually around 20-21mpg. I won't do it again though - I did not buy the car to putter around.