should do a full tune up before you start watching your mpg. Do your fuel filter at least. What is your tire pressure at? when was your last oil change? how are you measuring your mpg?
I installed a gm performance cai and it did nothing for fuel mileage. I also installed the gm performance catback and that did nothing as well.
2009 Ford Escape Limited - 3.0L, 6 speed auto, 4x4, 25/33 city/hwy imp mpg.
2017 F150 XLT-XTR - 5.0L, 4x4, 3.55's, E-locker, xtr chrome package, fx4 off-road package.
20/25 imp mpg