Mileage

[Chubosco]

I had an 05 H2 that got 14.7mpg and traded it in, now I have an 06 H2 that gets 11.7mpg. I bought both used so I really don't know why the difference.

But I am really thinking of getting crazy and spending 2 grand to put headers, catback, and modify the air intake.

That may seem crazy but I plan to keep this H2 for life. I don't drive it a lot. It is my baby.

Does anyone know how much the additions would increase mileage? I can see the increase in horsepower but mileage isn't clear at all.

Best guesses welcomed.

[tyler1bo]

I am wondering the exact same thing. My '08 SUT currently gets around 10.8 or so mpg, TERRIBLE!! 14+ would be a big difference to what mine currently gets and I don't really have many mods to it other than 35" tires and 20" wheels. I was also wondering myself what I could possibly add that would keep the truck from expending so much gas to push itself.

[Camou2]

We all own a Hummer because we love the truck and not because it gets good gas mileage! If you only put about 7,500 miles a year on your truck it would take about 5+ years to recover an investment of $2,000 today if you could achieve a 3 mpg improvement.

The best improvements in mpg will be achieved by how we maintain and drive the truck: don't load it up with excess baggage and weight, use cruise control on open roads, accelerate at a reasonable rate, coast to stops instead of braking, check tire inflation often, don't run oversized tires, change oil, air filter, etc. often.

Probably the only aftermarket item that will improve mpg is a cold air intake. Not sure how much but maybe there are test that have been done that you can Google.

[guruerror]

Nothing really helps as significantly as 'how' you drive it. The first thing I did was put a CAI on mine...it might have gotten me .2 or .3 more, but that's about it. I was more impressed with the way it subtly changed the sound and the slight increase in pick-up...but those two things tend to make you get into the pedal even more...so your mileage will actually suffer.

I was on a mission to get 14-15 mpg years ago when I first bought the truck, but then I realized that it just wasn't going to happen. Now I simply don't care...the truck's awesome...it is what it is.

I keep hoping that the 'huggers' will eventually develop a way to run a combustion engine on some alternate fuel (besides flex); like dog farts. Man, I'd be a happy camper then 'cause my pup's got some bad gas...then and all the great, American SUVs would come back.

[Luv2Camp]

I am getting 11 miles on average. With the stock set up intake I was getting just over 10. I had a CAI on the truck when I bought it and did not like having to oil the filter and likes the stock set up so I converted to stock and had an immediate drop in MPG from 11 to 10. I noticed that on the CAI system, the mass air flow sensor did not have the mesh screen on it. I removed the mesh screen on the stock one and the MPG went back up to 11. I remember doing this same thing on my Corvette years ago as the mesh screen really cuts down the air flow. It does leave the sensor wire exposed but as long as you have an air filter, there should not be any debris getting in there to begin with.

[tyler1bo]

What gas are you guys currently running?

[guruerror]

93 Sunoco as much as possible...it's my favorite.

[Luv2Camp]

87. Also use 87 when towing my 3500 lb trailer and zero knock or ping...

[NJ H2]

Originally Posted by Chubosco

I am really thinking of getting crazy and spending 2 grand to put headers, catback, and modify the air intake.

I have contemplated headers for a while now. Not so much for MPG but Performance. If you do go for the headers don't waste you money on shorties and make sure you get Long Tubes

[PaHumBug]

When people ask me what my mpg is I reply that I don't know or care, that's not why I drive it. BUT, I get about 10.2 on this one, which is lifted and modded (CAI, exhaust, tune, 6" lift, 37" tires (plan to go bigger once these ones wear out), gears, etc). My previous stock ones I got over 12 mpg. It really depends how heavy your foot is, and how much you care about mpg... I tend to have a light foot, more so because I don't like beating my baby vs trying to be fuel efficient... I use 87 octane too.

[chadley]

Im about 1/2 way thru a tank on my 07 and currently averaging 15.4mpg.(yes its a H2) Ofcourse that is driving like an old lady with a painful blister on her right foot!
I also live in the mountains at about 7500 feet, would high altitude give you better mpg?

[tyler1bo]

My CAI hasn't done anything..haha. I'm getting 10.4 currently with the mods listed below..I think it's mostly due to all the city driving I do. I live in a small town where it's a constant stop and go, not good for my case. And I must have a hell of a foot!

[Chubosco]

Originally Posted by chadley

Im about 1/2 way thru a tank on my 07 and currently averaging 15.4mpg.(yes its a H2) Ofcourse that is driving like an old lady with a painful blister on her right foot!
I also live in the mountains at about 7500 feet, would high altitude give you better mpg?

The thinner the air, the less milage I would think.

My catback system has been on for a few months now. I went from 11.7 to 13.2.

After reading replies from this post, I am going to remove the screen from the air filter and hopefully jump up another 1 mpg.

At 14.2 I will be a little happier and if I would quit driving 70+ on the freeway, I could even go slightly higher.

[SmokeyJoe]

I was getting on average 10.8, driving fairly hard with a mix of city/highway. I have done a few mods and drive a little easier (not much) and I am now getting 14.2. But mostly I am getting 13.4 after the mods and driving the same as before. If I am on the highway and set the cruze and reset, I can get up to 16 if I go 55-60.

Mods - CAI, Exhaust, programmer (performance tune), better plugs and wires and electric fans

[HummerJim]

How you drive affects highway mileage a lot. On the way up to Michigan on dry pavement last month I was running 75 to 80mph and had all the seats full and got 10.9 mpg, on the way back it was raining almost the entire way and with the traffic and only two of us, I was running 60 to 65 mph and got 12.6 mpg. Pushing that brick through the air takes power!

[Big.Z.hummin]

Anything over 12 mpg is a huge win in my opinion. most of the time i just dont even check my mpg. when I'm in Nashville if I drive like i have no pulse then i get 11.1 to 11.4. when in dallas i get anywhere from 7.8 to 9.0 at very best. D*mn all that traffic and red lights to hell

Granted i have a good amount of added weight, I dont understand how anyone gets over 13 mpg daily driving.

[MVR 155]

I brought my 08 into the dealer about 2 months ago complaining for the 3rd time about hunting for gears at low speeds and rough idle on cold starts, this time they actually reflashed the PCM with a different tune/parameters which helped a little bit...... it does not get driven much and to be honest with the nicer weather and gas prices its been parked more than usual (been driving the Z06 here and there). I had to drive it more over the last couple of weeks bringing my wife and M.I.L. to the airport and picking them up as well as working on one of my properties hauling stuff around. I noticed that I had significantly more miles on my trip odo. and hadnt used as much fuel. Gassed it up the other day and checked my mileage and got just shy of 13mpgs. Got 50 miles on this tank and the needle hasnt even come off of full yet. Im guessing a combo of the warmer weather and the reflash have helped. Previously I was typically 11-11.5mpgs. I do drive it easy as there is no point in putting your foot into it, its a 6700lb. pig not a race car