Light background, 1984 FJ60 with a 89 5.0 mustang HO motor that is mildly massaged (69 351heads and a fairly fat cam)/C6/203/Stock tcase. 4.11's 35's I get about 11 mpg with this setup. doesn't really matter what I do, I get about 11 mpg, highway, in town, pussyfooting it, enjoying the motor, etc.. It passes smog with flying colors. No codes thrown, almost everything is brand new in this motor including the O2 sensors. Timing is set to ~13 IIRC (or whatever stock is supposed to be) These motors in a car got up to 28 mpg (verified) while out on the highway.. I would love to see 16 or 18.. All of the smog stuff is intact. And will remain there. the actual air pump was supposed to route into the heads. I have it set up to inject into the exhaust. upstream of the PS O2 sensor. I am wondering if this is one of the problems. Perhaps the O2 sensor is getting too much air and making the engine run overly fat (does not really seem to be but). I just have a hard time thinking it is the problem because the motor is designed to run this way.... Is the C6 that much of a gas hog? No overdrive or lockup could be the issue I guess. I could swap it out to a AOD. That would not be too tough to find. But I would hate to swap out a fairly bulletproof tranny for one that will need a lot of love to be anywhere close to as strong..