in my 2.0 2dr i'm getting aprox 400km per tank, city and highway don't change much.. i run 31inch tsl swampers, 5spd and stock 4.62 gearing.. i think that works out to around 13-14l/100k. if i manage to keep the needle at 90km\h (actual speed of 100km\h) the mileage is a little better but it just feels so slow..
opening up the air intake and exhaust will result in improved highway mileage. jdmcrx, i would measure those tires, i bet they aren't touching 29 anymore unless you've changed them at some point....