[HummerJim]

The biggest reason is WEIGHT, the curb weight on the 2008 AWD Escalade is 5565 lbs vs 6400 lbs. for the Hummer H2. The axle ratios are different too with the Escalade's 3.42 vs. the Hummer's 3.73. There is a previous thread about the Escalade and Hummer having different shift chips for the Hydra-matic 6L80, also the Escalade is more aerodynamic without the trademark Hummer, almost vertical windshield. I've notice a slight improvement in highway mpgs for the H2 by removing the roof racks, which I never use and making it easier to fit in some parking garages.
This weekend gasoline @ $2.19 a gallon at Walmart in Washington, MO and $2.42 for premium. They had cars lined up for 200 ft., even though it was $2.29 at the BP across the street.