As another statistical information point, I had a '99 Suburban 2500 / 3/4 ton, with big block Vortec 454, 4L80E, 3.73 gears, 33" BFG all terrain tires & 'autotragic' 4x4 for about 6 years. I admit I have a heavy right foot, but mileage was pretty abysmal: I got 9-10 mpg on the highway, not...