Since gas prices are not going to fall any time soon I am thinking about getting a k&n filter to help out. What I reallly want to know is how much of an increase, if any, have those of you with the filters seen in your G6? If it is around 2mpg like most of the "Testimonials" on the k&n site say then I think it is definately worth the purchase.
Not sure about the G6, but the one in my Focus has 55,000 miles and has been "cleaned and reacharged" twice and still works like a champ. I never really notice that much in MPG, maybe 1 or 2 highway like Fusion stated, but I think I noticed an improvement on off-the-line accel and pickup. Even if it doesn't do any of the above, like Hambone says, it'll be the last air filter you'll ever buy for that car.
According to the 2006 Owners Manual that some cool guy sent me, the airfilters for ALL the engines (2.4, 3.5, 3.9) are all the same, AC Delco P/N: A1615C
Unfortunately, this has been found not to be the case. Something unusual has been found between G6's - two different air filters have apparently been used on the GTs but no real reason has been found.
Most of them actually come from the factory with an A2930C, even though the manual says A1615C. The A2930C is quite a bit larger than the A1615C. The filter that K&N lists on their site cross-references to the A2930C.