It is unusual if I get under 400 miles per tank. The most I've gotten was 508 (11.8 gallons at fillup), on a trip back from Pa. and five days of back and forth to work. I typically drive at 70 and use the cruise control when on the highway. I have an SE sport with manual trans and grill shutters, run 40 psi all around, and use 0W-20 synthetic oil. Since new (23000 miles) its averaged just over 36 mpg.
I work at Ford and know quite a few other Focus owners. It has been my very unscientific observation that the manual transmission owners seem to get slightly better fuel economy than those with DCTs. I don't think the difference in rpm at cruising speed makes as much difference as most people think.