I have a 2003 hummer h2 I replaced the air intake manifold and im getting 14 in the city apposed to the 11 I was getting before replacing the part..

 

Drive a ton around town with little 2 mile round trips.

Get 9.8 average to the tank.

If I'm driving straight highway I get about 11.5.

Only mod I know of is my exhaust. Just bought it and it has a cat back. Haven't gotten underneath to see what it is, but sounds nice.

Run 87, but it's Pennsylvania, so the amount of ethanol is ridiculous.

 

Just broke in our new to us 03' Adventure with a 1450 mile road trip. It is currently stock besides the 35/12.5/18 TOYO MT. We cruised at 75mph for a big part of the trip and averaged 12.5 mpg loaded with all our gear and 3 kids, once we slowed down to 65mph for another stretch we averaged 13.5 - 14mpg. Not much less than our stock 03' Escalade with the same motor (1500 mile trip averaged 16.5mpg). The hummer has NO areodynamics what so ever, just cleaning the bugs off the windshield you could tell it is sitting straight up with not much slant (rack). I was just impressed with the ride on such a long trip. Couldnt be happier.

 

Prior set-up included a Magna Charger - it actually improves highway gas mileage about 20%. You could cruise at 80 to 85 MPH (In Texas we have highways that allow that), and still get around 13 to 14 MPG.

With the present set-up (bored into 427, cam, headers, Magnusun TVS 2300 supercharger, meth kit), if I take it easy on the highway (keeping it no faster than 80 to 85 MPH, it gets around 10 to 11 MPG. Mind you, since it's still work in progress, I have not taken to the track yet, but, on the dyno, but the truck can cruise at around 150 MPH in 3rd gear. Average fuel consumption has been around 7 MPG, witch is not bad, considering all the mods. Currently we're in the midst of upgrading to 8-rib belt set with 8-inch harmonic balancer, and next week we're upgrading the front and rear differentials with different gearing. But hey, when you have a Toy Hummer that can smoke most sports cars off the line and gets the 1/4 mile in 12 seconds, who cares if it does 10, 7 or 5 MPG.

I will report soon about new fuel consumption number.

 

had mine a week now and average reads 12.3 all city driving, bone stock