Hey all I started a thread a few years ago when i first bought my H2 and didnt get
much in the way of useful info other than if you bought a hummer dont worry about
mileage lol But im still curious especially since gas has gone up so much.

This is my 1st and only LS motor ive ever owned. everyone raves about them.
i dont dislike it, and ive heard great things about longevity etc as long as it doesnt
have DOD. But totally not impressed with power etc. Yes i realize how un airodynamic
the H2 is, yes I know how heavy it is, Yes I know its full time 4x4.
ive had many many lifted trucks that never got this bad gas mileage. Ive gotten 15 MPG
and better with a 1 ton 454 on 40s , with cruise control at 60mph, at least as heavy if not more
than my H2. I own a 2 door tahoe since new for over 30 years with an amemic 245 hp totally
stock motor with 35s (300K miles on motor), only 3.42 gears that will blow away the H2 in a race and overall
drive ability and it will get damn near 20mpg with cruise control I doubt that tahoe weighs
1000 pounds less than H2, maybe a bit more areodynamic and yes is not constant 4x4.
The best ive ever gotten is 13mpg with cruise on at 55mph 60 knocks it down to 11
forget about 70 which is the minimum speed cars drive around by me lol maybe 8-9mpg

again just curious, no check engine light 90k on truck,runs great, love truck, nothing like it.
just horrendous mileage, again i think more of my question is ive heard for the most part
all LS trucks (not cars) get bad mileage. since this is the only LS ive ever owned I cant say.

lately i owned a bunch of new V6 powered chevys that are awesome in power and get pretty decent
mileage, MY ZR2 colorado on 35s with again only 3,42s im pretty sure , gets 22-24mpg yes not as heavy
but no lightweight 5200lbs i think.

Again my question still is with a superior motor and fuel injection etc.... How in the world
are all the H2s 10-13mpg at best, just doesnt make sense to me.

sorry so long This is just a curious question
and even though I know its just ball breaking but if you have nothing to say but sell it or if you
bought an H2 and care about MPG your an idiot, lol

 

Only drive downhill with the wind at your back!

#1- LOSE WEIGHT (I've removed my rear seats, spare tire & mount, jack & kit, nerf bars,etc)
#2- DRIVE LIGHT (remove everything inside that you don't need that day)
#3- INCREASE TIRE PRESSURE (start with a few psi, check ride & monitor tread)

AI Overview:

1. Master Your Driving Habits

• Avoid "Jackrabbit" starts: Accelerate gently and smoothly. Try pressing the gas pedal as if there's an egg resting underneath it.
• Anticipate the road: Look well ahead so you can coast to slow down instead of relying on last-minute braking. Braking wastes the momentum your engine worked to build up.
• Use Cruise Control: On the highway, engage cruise control to maintain a steady speed and prevent your foot from subconsciously fluctuating on the throttle.
• Limit Idling: Idling gets 0 miles per gallon. If you're going to be parked for more than a minute, turn off your engine.

2. Routine Maintenance

• Check Tire Pressure: Under-inflated tires create rolling resistance, which forces your engine to burn more fuel. Check your specific PSI on the sticker located inside your driver's side door jamb.
• Keep Filters Clean: A clogged engine air filter starves your engine of air and hurts efficiency.
• Upgrade Your Oil: Switch to fully synthetic motor oil, which reduces engine friction and can yield better fuel economy.
• Tune-ups: Ensure you change spark plugs and clean fuel injectors according to your vehicle's manufacturer schedule.

3. Reduce Weight and Drag

• Declutter: Empty your trunk and back seat of heavy, unnecessary items. Heavier cars require more energy to move.
• Remove Roof Racks: Take off bike racks or roof cargo boxes when you aren't using them, as they cause aerodynamic drag.
• Manage Your A/C: At highway speeds, using your vehicle's Air Conditioning is generally more aerodynamic and fuel-efficient than driving with the windows rolled all the way down.

 

The tech on these older engines was not as advanced and gas was way cheaper, hence the lack of power and gas mileage. The big automakers have worked some real magic to get a powerful V8 that will deliver 22-26 MPG in a huge SUV. I have a GM SUV with a 6.2L V8, and it was awesome -- until the engine failed at 60k and had to be replaced. The replacement is still awesome, and GM says they worked out the kinks in the design in theory. But do I think it will last past 150k miles? No...

There is so much unproven tech has been thrown at those V8 engines by GM, Ford, and Stellantis to get great gas mileage, that I am confident they will not last as long as the LS in our H2s. Like when I was young I learned that turning the engine off and on causes wear as oil needs to get to the cylinders. All these new V8s shut off at every stop sign and stop light to save gas... that is additional wear and tear.

You may have read that all the US automakers are having engine issues with their V8s and there are some class action lawsuits in the works. Having gone through this myself, I would say the most trusted large SUVs were built before 2015. I still wish I had not sold my 2011 Chevy Tahoe or my 2014 Escalade -- most reliable SUVs I had, after the H2 which has been bullet proof.

That being said -- you can install a duramax into the H2 to get more torque and power. It is costly due to the labor hours, but gas mileage does not really go up.

You can also get the H2 LS tuned for way more horsepower. Both Ligenfelter and Hennessy have packages to dramatically upgrade the OEM stuff.... but I don't think gas mileage goes up.

 

@hummerz Got it right... only things I would add...

* Smaller wheels have less weight. If you go with the original 17" wheels, you can save. If you move down to 15", you save some more.
* Upgraded wheels and tires add weight and rolling resistance which hurts gas mileage (estimated 30% factor to gas mileage). If you stick with OEM wheels and use highway tires instead of all terrain tires, you can improve your gas mileage
* Consider removing the rear spare tire and tire carrier as that is a lot of weight to carry. When they are on the back of the vehicle, they also increase drag as the air does not flow easily over the tire.
* Consider removing the front tow hitch if you have a front license plate -- that thing is 15-20 lbs of steel that most people will never use

 

My opinion is aerodynamics being one of the largest contributor's for poor mileage. these trucks were built for off-road capabilities, not mileage.
Large open wheel wells, a front end designed for 40* approach angles capable of climbing an 18" wall, close to straight up windshield, square box with no way to resolve the low pressure area at the rear of the truck when at speed, etc........
Mine gets its best mileage on the hwy at around 60 to 65 in my opinion but around town i average 10 mpg so it almost has to be the full time all wheel drive.
My 15 escalade gets around 12 in town but will do 20 to 21 on the hwy.

Neal

 

it probably boils down to the 4.10 gearing. the engine has to rotate 4.1 times for the wheel to go around once.
i dont know how much weight reduction really saves. i have removed the spare tire, the jump seat, the rock rails and side steps, and the under skid plate and tranny cage. i still get about 8 in city.
i think if small amounts of weight mattered then we would see better MPG's as we consume more fuel from the 32 gallon fuel tank but it does not change that would be another 195 pounds when full.

 

Driving More Efficiently-U.S. Department Of Energy
As a general rule of thumb, every 100 pounds of additional weight you carry reduces your vehicle's fuel economy by about 1% to 2%.
This effect is most noticeable in stop-and-go city driving where your engine must work harder to continuously overcome inertia.

 

I have a heavy roof rack with the spare tire and lights on the roof, my H2 is the opposite of aerodynamic, I average about 8mpg. Last time I put gas in was $117. I have a theory that with all these AI data centers going up, it will increase the cost of power so much that electric vehicles will become too expensive to charge and gas vehicles will become the cheaper option, it's anyone's guess at this point