First off.
You drive a vehicle with the aerodynamics of a brick........
Good gas mileage is not an option.
Secondly
Check
Tire pressure and balance
Front end Alighnment (TTB's are notorious for needing them often)
Oil and cooling systems for proper use and clean fluids
Inspect Engine belts and pulleys for wear and freedom of movement.
Clean your engine off. A clean engine runs cooler and more efficient
Change or clean out (K&N)your air filter.
Check plugs, wires, cap, and rotor.
(Just take off your cap, Does it look like something you could eat out of, if not,
change your plugs, wires, cap, and rotor)
This is about all there is, short of and intake and exhaust system upgrade,
to get the BEST gas mileage out of a brick.
Note: I keep up on all of this monthly and I only get 9.4mpg on average.
but then again mine is more the shape of a cinder block
/