I have an 05 GXP with about 8k miles on it. I drive about 75 miles round trip to work (mostly interstate) and average about 18.6-19.5 mpg. Couple of short highway trips showed about 21-22mpg taking it easy (60-65mph). Only time I see the 24 advertised on the sticker (or more) is coasting down a big hill !!! I can't say I'm upset over the mileage but I agree that the sticker is a little "exagerated" maybe????? Oh and I have put 40 series flowmasters and a k&n drop in in mine ..... no changes to the air box yet and only saw maybe a half MPG increase with those changes.

P.gxp was that the drop in filter and if so could you shoot the part # at me. Is it listed for our car? And yeah mine gets about 14-16 mpg @ 93 octane , but I cant leave that throaty GXP exhaust alone >

If ya cant find the box it will be on your receipt and printed on the formed rubber gasket of the fiter??thanx

thanks GXP I think some os these smaller town parts stores just dont the thing in their computer cause it'* not something they carry.Now if I can find ceramic brake pads for the larger calipers, GM dealer doesnt have them listed ...but willing to put them on. Which surprised me because most things I ask them comes back with the standard"that will void your warranty".

I've only got about 1000 miles on mine, but I'm seeing about the same on a 60 mile round trip commute. I'll have to double check, but at 75mph, it'* running 2300rpms(?). That'* pretty high for a V8. I think the mileage could have really been helped by an extra gear.

Ya the rpm is kinda high on highway. with the 3.71 final ratio could have used another gear....But The N* takes it stride,. Mine is really opening up for me quess it takes some miles to for everything to seat. I drop in the K&N filter and didnt help mileage, or maybe it influenced my foot. Had out of shop this weekend and got worse mpg yet 13.7. At $2.79 a gallon for 93 octane. IT'* KILLIN ME