1999 toyota solara gas mileage question?

I own a 1999 Toyota Solara SLE V6 and im getting extremely bad gas mileage, I went to my mechanic and he said mechanically the car is in excellent condition and he has no idea why im getting such poor gas mileage, around 10 miles a galon, my car holds 18.5 gallons and i go about 185-190 miles in the city on a full tank of gas. I drive normal, no speeding and wreckless driving and such. Would anyone have any suggestions of what i can do, my car had a tune up about 5 thousand miles ago and i just put in a good air filter. I was thinking would a K&N or Injen cold air intake improve my gas mileage?