not that much a fuel mileage difference between forester and legacy.. I have had both
the 95 Lego automatic I had, i put forester struts in and ran the 15" forester wheels.. got around 27-28mpg out of it on average.
the 02 Forester, pretty stock, also automatic, ran around 25-27mpgs, depending on the season.
i think i am getting slightly better with the 04 Forester, but it is a 5spd, lol