Toyota Repair: 05 avalon mpg, air fuel ratio, air fuel mixture

Question
I am currently getting 12-13 mpg on my 05 avalon XL. any ideas what could be the issue? I got a new engine filter and it didn"t help.

Answer
Mileage depends on a lot of conditions and can vary due to these conditions.
Tire pressures (too low or oversize tires)
engine performance (may need tune up)
Worn timing belt (retarded timing)
check engine light being on( due to rich air fuel mixture or air/fuel ratio sensor malfunction)
Climate conditions
mostly stop and go driving
grade and brand of fuel(some regions change their fuel blend seasonally)
low octane fuel
driving habits