Two Bricks in the Wind: Chevy K10 Big Green vs Hummer H2 Worst MPG Shootout (Video)

chevy k10 hummer h2 overland project truck mpg  shootout
Chevy K10 “Big Green” vs Hummer H2 Overland project truck mpg shootout

Which truck gets the worst mpg? We put our own Big Green and Hummer H2 against each other on our highway mpg loop. Both of these trucks have been updated to be, or are in process of being, more off-road worthy. This doesn’t bode well for efficiency, especially given our test loop resides at about 5,000 feet above sea level. Still, it would be fun and informative to see what kind of fuel mileage these bad boys get. The results will likely be some of the absolute worst mpg numbers we have seen during our testing.

Starting life as a 1985 Chevy K10 half-ton 4×4, Big Green now has a Chevy Performance ZZ6 crate engine. Rated at 405 horsepower (@ 5,600 rpm) the 350 cubic-inch V8 now has a FiTech throttle-body fuel injector and a MagnaFlow exhaust system. The big Chevrolet K10 came with a Saginaw 4-speed manual transmission and a 3.73 rear axle ratio. As is, the gearing, tire size and overall character of Big Green makes for a truck that’s as happy as a clam under 65-mph. This particular test is on our abbreviated 65-mile loop, running at a constant 70 mph.

1985 chevy k10 big green engine swap

Lightest amongst these two trucks, Big Green has Mickey Thompson Baja MTZ mud-terrain tires.

Normally, we do a 98-mile loop, but filling up these trucks twice is tremendously expensive and it’s something we opted to avoid. This is especially noteworthy for old Big Green as it is a little harsh on the driver. It shakes, rattles and whistles as you rumble down the highway.

TFL team at Overland Expo

Our 2003 Hummer H2 comes with a 316 hp, 6.0-liter V8 that makes 360 lbs-feet of torque. It has an aftermarket exhaust system that may help a tiny bit with power and throttle response while it sounds glorious. It has a four-speed automatic transmission and 4.10 gears front and rear. Fitted with brand-new BFGoodrich KM2 off-road tires, the Hummer is at a weight, tire and aerodynamic disadvantage.

In this video, Andre and Nathan set off near Hudson, Colorado to run the abbreviated mpg loop in our two favorite trucks. While the topic is somewhat mundane, the video results are quite entertaining. Enjoy and tell us what you think.

Nathan Adlen
Easily amused by anything with four wheels, Nathan Adlen reviews vehicles from the cheapest to the most prestigious. Wrecking yards, dealer lots, garages, racetracks, professional automotive testing and automotive journalism - Nathan has experienced a wide range of the automotive spectrum. Brought up in the California car culture and educated in theater, childhood education, film, journalism and history, Nathan now lives with his family in Denver, CO. His words, good humor and video are enjoyed worldwide.