This is the only place that no one will respond to my question with "Duh, you bought a Hummer, that's why"

I have an '06 H3 lux/off-road package 285 tires, and thought my mileage was pretty bad. I finally set my trip odometer when I filled up last time and I've gone about 150 miles and I am almost on empty now. Now, these have been exclusively city miles, strictly back and forth to work and to the store. No highway driving to speak of.

I admit, I have a habit of hitting the gas kinda hard when I start from a stop and tend to gas a little more than needed, but nothing that I would think would cause this kind of guzzling. Is there something I need to have checked out or do I just need to REALLY change my driving manner?

Still love the damn thing though, not one problem in the snow this year in Pittsburgh.

Any help appreciated, thanks.

 

A lot of people on here are claiming lower MPGs due to little things like adding roof racks, bigger tires etc. But i cant see an h3 being affected that much by those sort of things. Are there any other issues like lack of power or anything?? If you're low on power there oculd be a number of things causing poor mileage. (here's my "captain obvious" statement) Thats half of what other people are claiming in the MPG threads...

 

My 07 Lux has 285s as well. Like me, you probably assumed they are stock. I went and got a build sheet from my dealer and they are not. They were an optional upgrade but the only way to tell is from the build sheet. The dealer should print you out one for free. If you came stock on 265s like I did, your speedo may be a little off. Probably not enough to make you show 7mpg, but some. The worst I have shown on a tank is 15.1. I am going to find someone to calibrate my speedo for me. I think someone with a programmer can just go in and put in the new tire size.

Look for the recent thread on cleaning the throttle body. I think that can make a pretty big difference on mileage. I'm doing intake and exhaust on mine hoping to grab another 1 or 2 mpgs. Beyond all of that, the driving manner you mention will take it's toll. These are heavy rigs. I can imagine if I were getting into it pretty hard I could see the gas gauge falling.

 

I have noticed a little power loss at times when idle at a light or stop sign. lights will dim a bit, maybe that's why I'm a little heavy on the gas at take off. Doesn't seem like much though. I don't smell any kind of leaks, gas or exaust. Taking it to the dealer for inspection and service this weekend. I asked them to check it out.

 

i have 06 lux/offroad package - mine has the 285 series tires, i was curious about the tire size and mpg - i looked at the little sticker on my door and my tire size is correct im getting anywhere from 15-18 mpg on mine which to me isn't bad at all but im also in buffalo gas prices are going nutzzzzz almost 4$ a gallon here lol

 

There are many reasons that will effect your MPG is such a drastic fashion. You could have a bad head (2006 H3 are notorious for it), stuck open thermostat, clogged injectors, dirty Throttle Body, faulty MAP sensor, etc.

Are you getting any DIC (driver information center) lights or messages?
Go to your local auto parts store and see if they can pull any "codes" for you from you diagnostic port.

Then report back to us. It's all guessing until we know what codes you are throwing.

 

the only codes I've seen are when I was getting the "Door open" for a week straight and SVC TPM started about the same time. Lasted about a week and then both went away. Seems to be driving fine, but maybe I don't know any better because I've only had it for a few months.

 

16/17 average mpg steady driving with up hills and city and occasional bursts of speed. I think it's reasonable mileage for an H3...But 7 mpg is way too low,even with lots of city driving..

 

Not sure what's going on with my mpg either. My first full tank of gas 4 months ago included a half day of wheeling plus a fair amount of highway and some city - 17mpg. Since then I occasionally remember to reset the trip odometer at a fill up, then remember to check again at next fill. My mpg has been slowly but consistently dropping. Last I checked it was around 12 or 13, rough in-my-head estimate - too depressing to use a calculator.

When the weather warms up I'll do all the maintenance stuff whether it appears to need it or not. Plugs and wires (I'm at almost 60k miles and they are supposed to be good for 100k, but I'll do it anyway), air filter or air doc + new filter, all new fluids - if it's wet and can be changed I'm changing it, clean the throttle body, etc. I may even take it to a shop and have them check/service everything I can't or don't want to do such as cleaning the fuel injectors. I'll probably even seafoam it.

 

I have 06 with 315's, roof rack, leveled, heavy load in the back etc.. all things that drive my mpg down. When bought off lot stock I was getting 18 ish. I drive probably average, gas when needed, I deff don't pamper it but don't rod it either. My mpg went all the way down to 13 with the mods. I have tried to counter this with air intake mod, pcm for less, keeping tire pressure regulated at 38 with bi-weekly checks, running speed limit, new shocks and miliage has crept back up to avg. 14.7 to 15.5. I agree that you have something else going on. I don't care how hard you are gassing it. Make sure your not stuck in 4wd hi, some of the switches have stuck before and sometimes the lights go out.. cycle it to check. Ck how long it takes for your's to warm up to norm op temp. Agree could be thermostat but still dont think that would drive you down to 7? possibly... may have a couple things going on. May have to buckle down and take to the steelership... Pay it now or pay it with the bad gas miliage. What ever is going on it can't be good on the engine either if your running that rich for what ever reason. Keep us up to date with what you find.