We get anywhere from 10.5-12.5 with combined driving.... obviously lower in the winter with warming the car up and longer idle periods. In the middle of summer I usually tow my jet skis back and forth from the lake at least once so that all figures in there. On our road trip to Florida this summer my best was 14.48 (all highway).
The Hummer H2 is not an economic vehicle by any stretch, its around town mileage is not much worse than any other 3/4 ton + truck but with its superb aerodynamics (being sarcastic) it does suffer worse than others on the highway.
I agree with the above comment on how much you will be driving it annually to figure your total fuel expenses, if you are honestly this worried about fuel you may want to pass and this is why: If you are constantly worried about fuel it takes the fun out of driving one of these and second I can assure that gas prices will go up in the next 12-24 months...... its not if, its when. I was spending well over $100 to fill up when gas was over $4/gallon
Not trying to be a smart ass with my last paragraph.... just pointing out the obvious. If you need a large SUV but are ultimately looking for better economy maybe look at a Tahoe or Yukon with the displacement on demand..... my friend gets mid-high teens knocking around town (using E85) and around 20-21 on the highway with his loaded up 2007 Tahoe and its a very nice truck.
Good luck on whatever decision you decide to make
