I've got a 2006 3/4 ton Chevy with a 6.0L engine and I can tell you that, even on a good day, it will get about 12 mpg! That's no cargo, no towing, just me and my 35 pound dog driving down the road. I would guess it goes to about 7 or 8 when I'm towing my camper (28' ultralite TT). Don't use...