I just bought a 2007.5 LMM and have gone threw 2 tanks. I averaged 12.7 and that was 70% highway and 30% city streets. Now, the truck is lifted 6 inches on 325/60/18 but I figured I'd see 12-13 city streets and at least 16-17 highway. It's all stock except for the lift. I also have a P0128...