I know a lot of people in the group here are curious about gas mileage so I figured I give a report on the gas mileage on our trip to Tybee Island GA in my 03 H2. 300 mile drive there got 13.4mpg and 300 mile drive back got 13.3. That's hand calculated and filling up the exact same way each time. Kept speed between 70-75mph the whole way and had about 500lbs worth of people and gear. Modifications on Hummer are Airdoc intake with Airraid dry filter, Superchips programmer, and Flowmaster catback with cats deleted. Also truck just recently had a full tuneup and all fluids throughout vehicle changed. Was hoping for a little better gas mileage but can't complain cause it drove great and was very comfortable the entire drive. Plus it's a Hummer so we didn't buy them for the gas mileage.

 

I wish mine got that good of mileage I am happy if I hit 12 mpg

 

Consistently ~14 average here in CO

 

Mine is about the same, 12-13mpg in FL. My wife's hybrid gets 35mpg so household average mpg would be 20mpg or better. I am kind of happy....

 

went from Miami to Tampa . the MPG was avg 13.5-14 .. I compared the manual calculation and the truck gauge and were about the same ...
The Avg MPG displayed was less than 0.5 higher

No mod at all

Btw remember we dont have any hills here in SF . Avg speed 70 mph

 

I had 12.5 with all stock, but upgrading to the 37" tires I get 10.3

 

Sounds like my mileage then was about right. The only way I could see mine getting better than the 13-13.5 I got is if I had cruised at a lower speed but on that entire stretch of interstate I would have gotten ran over. Most people were driving 80-85mph.