Just bc its starts on first try good doesn't mean it doesn't need a tuneup. My friends hyundai started on the first try but had spark plugs that were shut, plug wires that were bad, a carbon buildup problem and a bad o2 sensor.
That being said, the first thing I'd try is running the engine up to red line a few times with the peddle to the floor. If you've driven your car too nicely it will build up a ton of carbon which kills your gas mileage. I floor my car once or twice each tank of gas to keep the carbon down so my gas mileage stays up. It couterintutive but it works. If that doesn't help it do a tuneup. new spark plugs, wires, distributor cap and rotor and maybe an o2 sensor. Also, buy a bottle of Chevron Techron and put it in the gas tank. you may just have dirty fuel injectors and Techron works best.
