Fuel Mileage
 

I got a 2006 H3 with 176k Km's. Gets around 400km per tank. ITs winter right now where i live(saskatchewan,canada) so we warm it up before we take it out. Just wondering what everyone else gets in there hummer!

You're on your own to convert to metric. I get between 13.5 and 14.5mpg.

Here's a couple threads that touch on either what people are getting for fuel efficiency, or thoughts on how to improve it:

https://www.hummerforums.com/forum/h...mmer-h3-28145/

https://www.hummerforums.com/forum/h...mileage-27548/

https://www.hummerforums.com/forum/h...age-mpg-28707/

https://www.hummerforums.com/forum/h...ter-mpg-28662/

https://www.hummerforums.com/forum/h...mileage-19406/

https://www.hummerforums.com/forum/h...mileage-30150/

https://www.hummerforums.com/forum/h...mmer-h3-30068/

Also, What fuel do you use? We put in premium , always have since we got a major service done on the hummer a while ago(fluids,filters,etc)

I get 12 with lots of extra weight, and 34.5 inch tires

I always have my rig loaded with tools and do all city driving...still avg 14mpg. I only use premium.

Just as it was advertised:

Fuel Economy of the 2007 Hummer H3 4WD

I get no more than 420 kms and no less than 380 kms off a tank in alberta. A tuneup to your Hummer does not warrant premium fuel. Ive tested fuel multiple times. Premium vs regular ive had NO difference in fuel economy and NO difference in power.
I have a 06 h3. 120k on body. 15k on new crate engine. With 285/75/16 tires.
Premium fuel is usually recomended for high compression engines which the 3 has.. But I have yet to see a difference.

I know it may not do anything. But I'd rather put fuel in thats better and has no ethanol, for 5 -8 bucks more a tank. and i can afford it. so why not

Just purchased a 2008 Alpha with 33" tires. First tank only got 10mpg of city driving. Ran a can of Seafoam through it and went to 97 octane. Interstate road trip over the Rockies was an amazing 19.5 mpg. Next trip into the Rockies and a few hours of breaking snow drifts and moderate hill climbing 14.5 mpg. Couldn't be happier with my v-8.

I live in new Brunswick. I got about 500-600km with mixed city and highway driving when i got it. i put heavier tires on and get a bit less but not that noticeable. I only run regular. Also i just cleaned my tb and maf yesterday and seems to run smother and have a.bit better response. Tb ws filthy. i figured roughly 16-18 mpg

Hummerz it does not call for premium gasoline. Just regular. That link you posted calls for regular also. I honestly don't know if putting a higher octane would gain any mpg or not. Maybe slightly. I don't think it really would be enough to make up for the cost of the premium gas though. And the horsepower? possibly a little higher, but I would think over the long run the premium is just going to cost more and not do much for your H3. Get a pcm tune, a one time cost and gain some hp's and mpg there. H3's call for 87 octane fuel. We run a tank of premium through periodically but we use 87 like it calls for everyday driving.

My post may be a little confusing. "Just as advertised" I meant the 14 mpg city driving, not the fuel grade.

Yes gm recommends 87 minimum in the H3, however GM highly recommends using "Top tier" gasoline. Switching to top tier, in the long run, will get you better mpg overall. Cleaner burning fuel, prevents carbon deposits, keeps the engine performance optimal=better fuel economy.

Here's a site that explains the fuel recommended by GM plus other automakers:

Top Tier Gasoline

Thanks. Sorry about that. I just don't know though in the long run if it really is a cost effective means, or if the benefits are of any major significance to use premium as your main fuel. It's something I've done some reading on in the past, but I really don't know what the answer is.

Because I know the amount of carbon buildup cheap fuel can cause on an engine, I always use premium, usually around 20c more a gallon. I always recommend to my customers, at least run 1 tank full of premium, for every 5 fillups. However it doesn't really matter what grade you use, if you get your fuel from a top tier supplier as stated on the site:

TOP TIER Detergent Gasoline Retailers

Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.

In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.

Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.

Top Tier Gasoline

Ok. Yes. I usually use Shell to fill up. sometimes costco if im in that end of the city. I'm thinking about just sticking to Shell Regular Gas and filling up a tank of premium around every 5 fill ups like you say

That fuel does a hummer good (same so with any vehicle)! I also use Shell, only available top tier fuel around me.. Some people "eat healthy", ....... My H3 "drinks healthy"! ;)

Ya there is a shell right by where I live. So i'll start just using shell regular for a while. I'll see if there are any mpg changes

15mpg,no mods

2008 Alpha
 

I have been around Hummers since they came out...and finally purchased one two months ago. Mine is a 2008 alpha running 285/75/16's. All stock... Ran a can of "Sea foam" through the system on the first tank, nothing else. My mileage has been running around 16 mpg in town and 19 on the highway. Was pretty amazed with the MPG and wondered how it did it. Looked for add ons from the previous owner..Super Chip, exhaust, whatever and nothing. Totally stock out of the factory. The only thing I can think of is driving with a light foot and not driving it like my "71" Chevelle. Beats me??

Installed a cold air intake and throttle body spacer and have noted a pretty good increase in gas mileage. Went from ~16mpg to ~19-20 which is pretty good as far as I am concerned. Now to get a re-flashed PCM and a good exhaust system and I will be good to go :D

Running premium when regular is recommended does not hurt the engine, only your wallet. You get no more mpg out of it since regular and premium contain the same amount of BTU's. Premium has additives that make the fuel better resistant against self detonation (pinging). That is mostly required for engines that run a higher compression.
If you have an engine that requires premium and you use regular. Two things will happen. Mileage gets worse and you lose power. The engine will adjust its timing, causing you to loose power (and to compensate you give it more gas, hence the worse mileage.)

Hello again. re adjusting my mileage. I cleaned the tb and maf . I filled to brim with gas and added injection cleaner. I drove 288 km and was five eighths of a tank left.

Worthwhile mileage reports
 

the only way to do meaningful measurements is; fill up; drive a long way; fill up and write down the gallons and miles driven( or km).
divide the gallons into the miles driven. you know,like 300 miles,15 gallons = 20 miles/gal.
your gas gage is pretty good,but no good for meaniingful reports or comparisons.

Yes, that's no way to know exactly what your mpg's are. You have to do what Happythree said. Then you will know exactly what you are getting. And the only way to know if you are getting better mpg's than before you cleaned those is if you calculated what your mpg's were before you cleaned them also. That way you would know if you actually improved your mileage. Otherwise it is impossible to know.

^^^^ This, There is no benefit in using premium in a Hummer H3, as they are NOT designed ie tuned to take advantage of the extra 'quality' fuel. The octane of the premium fuel stops detonation in highly tuned high compression motors. This is why performance cars generally require premium fuel.

Putting premium in a Hummer would be like putting lipstick on a pig, waste of money and effort, as the H3 engine is tuned and designed to run on regular fuel, and it is unable to take advantage of the added benefits that premium has to offer.

I love the people who say it's only $8 a tank or whatever, I can afford it....what a pointless thing, rather than handing the $8 to the servo operator do something else with it, I am sure no matter how much money you have you can always use it for something other than throwing it away on fuel that makes no difference what so ever, take the $8 and sit down and have a nice relaxing cup of coffee or something, give it to a homeless person, donate it to charity, send it to me.....plenty of options there.

I know that is no way to tell. I am going to put what i got out of the tank full. I haven't put any more in since. I sat idling alto though also because i do a fair bit of waiting. I travel ferries and pick people up from them. So i would get better results just straight driving. I have 384km on it and still above a quarter tank.

I get almost 500 kms on a tank.

tankathon!
 

i once drove 400 miles till the low fuel light came on,could have made 440??
i was 30 miles from home,didnt have the guts to try it!

Once the light came on so i reset the trip odo. Just to see and went another 60 kms. Without running out ran out the next day on my way to fill up tho. Lol. Most vehicles are made to go the extra 40 kms after the idiot light comes on.

I get 15.5mpg all HWY-(2006 H3).. That is with rancho 4in, 35in tires,PCM tune and Airdoc to help/hinder..
I used to get much less but took the roof rack off..

There is a noticeable difference in drivability and fuel mileage using Shell over everything else in my area, including Mobil. I try to stick with Shell if possible.

Hi,

I'm new here - first post.

I'm Chris from Germany.
If you run a H3 3.5L in Europe the power and fuel consumption is quite disappointing.

But there is a help.
Last week I've ordered a tuning software to get access to the ECU.
Today with great success I reprogrammed the spark map and did a gentle change to the fuel map - and surprise surprise - the engine has plenty power and torque at low revs and maybe needs a lot less fuel.
The injection values look very promising.
The next few days I will see how the consumption drops.
I'm heading for 23-23.5mpg.

Cheers
Chris

What software did you use?

I did the PCM tune and lost it after I took it in for warranty work. I know I can send it back to get it redone for free but I have no time to wait around without a vehicle. It would be nice to adjust the settings myself.

The software came from HP-Tuners.
HPTuners.com >> Performance At Your Fingertips

At the moment I'm on 18.8 mpg after adjustment with LPG fuel.
I think on 98 octane fuel it will need 20% less.

Just curious, how difficult (or dangerous) would a DYI pcm tune be for a newbie? I'm relatively computer savvy but only remedial auto knowledge. I'm guessing its mainly inputing the proper values? Or, is this something to definitely leave to a professional?

OK, I spoke too soon. I just checked out the cost of the software vs the cost of going to pcm4less. PCM4Less is the way to go. lol

As with all brain surgery - there is always a risk.
As far I've noticed the software has many safety routines to prevent damage.
Yesterday I had to remove the radio fuse to make the flashing going because the aftermarket radio had send signals the software did not know and so the writing was stopped.

The other thing is, you have access to hundreds of adjustments. What would you like to change and could this change be harmful to the engine?

I do tune engines for about 20 years (just as a hobby, not professional) and have now some experience with hopping up engines. Before I only did it with grinding, enlarging mechanical parts, other carbs and stuff.
This now was the first time I've tuned a modern engine with just a chip.

But it works so far and is easy done. But because it is so easy the risk of pushing it too far is there and could kill the engine.

Cheers
Chris

As with all brain surgery - there is always a risk.
As far I've noticed the software has many safety routines to prevent damage.
Yesterday I had to remove the radio fuse to make the flashing going because the aftermarket radio had send signals the software did not know and so the writing was stopped.

The other thing is, you have access to hundreds of adjustments. What would you like to change and could this change be harmful to the engine?

I do tune engines for about 20 years (just as a hobby, not professional) and have now some experience with hopping up engines. Before I only did it with grinding, enlarging mechanical parts, other carbs and stuff.
This now was the first time I've tuned a modern engine with just a chip.

But it works so far and is easy done. But because it is so easy the risk of pushing it too far is there and could kill the engine.

What I tune normally:


Cheers
Chris

Thanks Chris,
I had a feeling it would be something I should avoid doing myself. I'd rather not risk ruining my truck so I've decided to let a professional do the job.

Best wishes
JT

Hi,

a short video of the tuning result. It was taken with normal driving so I don't show the full potential.


I think it is a lot more fun now and the mileage is now at 19 mpg.