[War_Wagon]

I wouldn't mess with anything mechanical other than checking your timing, plugs/wires, air filter etc. My DX wagon averaged in the mid 30s with not too spectacular driving on my part, and it was pretty much stock. Check your front tires for uneven wear as an indication of poor alignment, and make sure none of your brakes are dragging as was stated before. If your car has the original cat converter on it, it could be plugged up, and the excess backpressure could be hurting you. Also, listen for excessive valvetrain noise, if the valves have never been adjusted you will hear a lot clacking under the valve cover and could be due for an adjustment.

As for driving, I found that my 1.5 had enough torque I could experiment with skipping gears while upshifting and keeping the revs low. See what works for your car and driving conditions.