In 2008 I drove 2004 Civic 15388 miles
> used 450 gallons
> got 34 mpg
> paid $3.06 per gallon ($2.60 in 2007).
Your MPG seems on the high side, per fueleconomy.gov (not sure exactly which sub-model of Civic you have, so it is hard to say more). You must be doing something right with maintenance, driving style, etc. :-)