09 GMC 2500 Crew 6.0 10" lift 37" Nitto Grabbler Mud Terrains 410 gears AFE intake,Bullydog.
If Im rolling down hill with a tail wind 9 to 10.
But it looks good doing it!

I also have a 2002 Ford F150 Crew King Ranch 12" suspension lift and 3" body lift,41" Super Swampers,488 Gears,and this truck gets 8 to 9. But again Sure is fun to drive

The Airboat is a 9x20 Diamondback 496 EFI, gets about 4 MPG When your driving it right