but its less rotating mass. stop and go it takes less power to move thoes wheels.. not having to give it as much gas would save gas in the long run i thought.. when i went from big heavy rims on my eclipse to 17volk gtcs i got around 34mpg all highway. i do have a gt35r on there and was never in boost before i was around 29.. i didn't change anything but the rims

 

Cool, so my first couple tanks with Mobil 1 and K&N Drop in have gotten 36.8 and 36.2 MPG(US). These tanks are mostly city with some highway about 60/40 split, different from my regular 10 city 90 highway. I suspect the better economy is due to the weather and the fact the engine just broke past 10,000 miles more so than the K&N filter, the Mobil 1 may have contributed a little bit but the other factors mentioned are of much greater magnitude