give it a fresh tune up. on mine all i have to do is change the plugs, i have the coils on plugs...
or try a fuel treatment... i was getting 13, just tried a prodect name called BG Products Inc. look them up on the web,
BG 44K® Power Enhancer®
that is what i just used in my last tank. i still got 13, but this tank i am at 200 miles and have a 1/4 tank left.