Why is your Daewoo lanos using to much fuel?

There could be all the usual things like tune up, too hard driving conditions, underinflated tires, etc. However, i have a Lanos and it's really not good on gas for such a small car. I bought it new, and it always gave dissapointing gas mileage. Our Honda Civic gets like 10 more mpgs! So don't expect too much from Lanos.