Just purchased and installed a K&N air filter on my 2.4L.
Hope to get better performance, but if nothing else it will be the last air filter I have to buy for my HHR. I currently have 22,450 miles.
I will post any advantages to installing the K&N opposed to a stock air filter after a few more miles, if there are any.

 

Replaced my filter w/ the K&N almost 8K ago. Only noticing an increase of economy of maybe 1 to 2 MPG. Which I've got no compaints about!

 

If I get a few more miles per gallon that will be fine with me. Well worth the $50.00 investment. I don't think it will be long before we are paying $4.00 / gallon for fuel.
Mileage was the main reason I traded in my 2004 Trailblazer for the HHR. So far I am very please with the mileage. I get right @ 25MPG in Houston traffic. 27+ highway.

 

Shop around on the net, they can be picked up for $37!

 

Check Amazon, Got mine there for $19 plus shipping. Total came to around $25.00

 

SInce im getting barely 16 mpg, I ordered one too, should be here in a couple days.

 

Are you getting 16 mpg city, or mixed?

 

99% all city driving. No warm ups, no excessive idling, correct air pressure in tires, no a/c on. 2406 miles on it so far. It's drivin me nuts.

 

I have an 07 2LT with 19k. I am pretty much a 50/50 split. Was getting 25-27 mpg before putting in the K&N. Mileage has pretty much kept he same after install. I would have the dealer look into that, my wife has an 07 Saturn Outlook getting better mileage than that!

 

I just dont know what they will do, I have called the local dealer ( not the selling dealer as they are far from me ) and they say they can check fuel trim, etc etc. I wanted to check for an update and the dude says there isnt one without looking at mine yet. Im really frustrated over this. The car runs real good other than the crappy mileage. I would hope to get at least 20 around town.