K&N Air Filters...?

Has anyone had any luck with K&N air filters?
I don't want to improve performance, I want to improve my fuel economy. I've heard that K&N filters can really help with that. If I get the extra performance, that's just a bonus.
I only get about 450km in the city off of a tank of gas. Is this normal?
Oh and by the way, what is the size of the fuel tank on a '93 Cavalier RS 3.1 V6?
A couple questions, but I didn't want to post two threads...

Thanks :p

93,13.6gallon tank.as for k&n,thats what ive always used,they seem to do well for me

I still have my drop in the evil black box one along with a 3" on my current intake.... mmmm K&N

I have always used a k&n on my car. I have a aftermarket intake with the 3 inch k&n on it. I couldn't tell you i saw the sifference in horsepower but they are nice cause they last and you can clean them. Also I get between 28-32 miles per gallon wiht it and that driving like your average 18 year old (a complete moron)

What is the size of gas tank on a 2000 2.2. I have a K&N cold air intake. What gas mileage should i be getting on a tank of gas? I dont stomp on the gas all the time, but the frequent stops at stop signs and lights might make a difference. Every once in a while, if i'm in a hurry, i'll give it some gas.