H1: used by military and Arnold; its huge like Arnold and only gets around 8 miles to a gallon or about the same gas mileage as Chevy duelly pickup
H2: The most popular civilian model. It is full time 4 wheel drive and can ford 2 feet of water at speed. It gets about 12-16 MPG, which is comparable in mileage to a chevy 2500, ford f-250 or a chevy avalanch
H3: The smallest hummer in the GMC line up. This truck comes with a choice of two engines: A 5 cylinder or the V-8. While the 5 cylinder is adequete, the V-8 Alpha model is superb at towing. The H3 is based on the colorado truck body and gets between 16 and 20 miles per gallon. The H3 can do everything off road that that H2 can do but with better mileage. The H3 gas mileage compares with an average america pickup truck like the chevy colorado, or ford f 150.
2. That Hummer H2 gets about the same gas mileage as a chevy avalanche.
3. The Hummer H3 is a nice ride with decent gas mileage; its too bad people stereotype the H3 with the H1.