my non modded 4g64 got around 20mpg city driving and I was around 26-27 on highway (I mean all highway whole tank)
Note when I originally bought the car the gas milage was complete crap. I replaced air filter, and got a new o2 sensors, cleaned out the throttle body. It definately improved after those items by alot.
Since I started adding stuff the mpgage went down a bit. I'm dreading when I finally bolt on the evo 3 16g I got in the garage come spring break. Ouch