The are probably a 100 things I could do to get better gas milage from my 98 SSEi. I am getting about 18mpg city....The car runs great.
What are some basic things I can do to boost that?
I heard K&N is good, so I put in their air filter.

K&N filters have a small flow advantage when new, but as they accumulate dirt they start to restrict more then a paper filter. So keep it clean,

If there is any basic maintenance that you haven't done, do it, but don't go replacing things that are still good. It'* easy to spend a lot more then you will ever get back in gas mileage. Fuel filter, PCV, oil change, air filter, spark plugs, wires, ect. You may want to try cleaning your MAF and IAC.

And the biggest thing of course is to get off the gas. Avoid heavy accelerating or braking. Avoid left turns, extra stops, ect.

Make sure your tire pressure is correct too. That affects your mileage as well. Even cleaning your TB can help, and your intake for that matter (depending on your engine...put it in your signature with your car and year).

a new O2 sensor gained me 2-3+ mpg

I put in a CAI, and had Intense-racing.com do me a reflashed pcm, pretty thorough tune-up, 180* T-stat and flowmaster muffler. All that at pretty much one time and I noticed a considerable mileage increase. Providing I can keep my foot out of it. It gets down to how efficient you burn the fuel.

Hope this helps,

Tim

PCV, fuel filter, sparkplugs/wires, tire psi, clean TB & MAF, K&N. Not to mention a O2 sensor like corvettecrazy had said; I gained 6-7mpgs on the highway after changeing mine which had over 100k on it

Ed

You wouldn't believe me if I told you, so I won't tell you.

As many mentioned, a good tune up, and general maintenance go a long way. As far as having performance and gas mileage......well..... if you pulley down and increase the breathabilty of the motor... you may see slight gains, however you will have a foot issue that overall decreases mileage.

It'* a catch 22.

Mac..PM on the way.

thats the key a cold air intake is only going to help your fuel milage if you keep your foot out of it. because you are putting colder more efficeint air into the engine If you pund on it the enging will demand more fuel thus resulting in less fuel milage.