I used my Hypertech to disable AFM on my truck as an experiment. SO many folks are constantly talking about oil consumption, AFM makes for WORSE MPGs, etc., that I thought I would give it a try. With AFM I get between 17.8-18.3 MPG Monday through Friday back and forth to work. I disabled AFM last night and topped off the tank this morning for the drive. I got 20.1 MPG driving to work, which is surprisingly slightly better than what I get with AFM on. Now I know weather, fuel blends, etc., have an impact on fuel economy as well, my driving back and forth to work at least takes the terrain out of the equation. I will keep the forum posted. At the very least, I don't have to hear the AFM turn on and off and hear it on my exhaust.