well my car has a diesel engine which is much more mpg friendly, plus it has 6 gears so even at 85 the rev counter is sitting at just under 2000 rpm, so i guess that's gotta help...plus the engine capacity is only 1900cc
one thing i could never really get about the cars in the states, and in aus too, is why the engines have such big capacities. i mean some cars have like 4 or 5 litre engines and yet their performance figures aren't exactly amazing. a subaru impreza has something like a 2.0 litre engine with a turbo and it's performance wipes the floor with many cars with engines twice the size...
having said that i doubt your honda civic has such a big engine jorgelito...what kind of civic is it - if it's the type r then that might explain why your mpg is so low, otherwise you could have something wrong with the engine? or may be that you just drive it too hard
