H3 gas mileage SUCKS

[sharkman]

I am trying to find out what the average MPG you are receiving on your H3. I have 5500 miles on the truck and have received AN AVERAGE of 14-15 mpg driving on the freeway. I have taken the truck to (2) dealers and neither can find anything wrong with the vehicle. As they say, "the vehicle is performing within specified parameters." Is anybody else experienceing the crappy gas mileage?

[sharkman]

I am trying to find out what the average MPG you are receiving on your H3. I have 5500 miles on the truck and have received AN AVERAGE of 14-15 mpg driving on the freeway. I have taken the truck to (2) dealers and neither can find anything wrong with the vehicle. As they say, "the vehicle is performing within specified parameters." Is anybody else experienceing the crappy gas mileage?

[FormerJeeper]

I'm getting between 17.5 and 19.1 MPG.
Mostly freeway driving.

-C

[sharkman]

Have you done anything to your vehicle? What speeds do you drive?

I added a K&N filter and a flowmaster exhaust (both are supposed to improve the gas mileage). Also, I have the roof marker lamps, a brush card w/ PIAA lights attached and the luggage rack.

[MxHonda]

K&N filter, Mobil 1 Oil, 3,000 miles, 18mpg city/hgwy AC on all the time... How heavy is your foot?

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by sharkman:
Have you done anything to your vehicle? What speeds do you drive?

I added a K&N filter and a flowmaster exhaust (both are supposed to improve the gas mileage). Also, I have the roof marker lamps, a brush card w/ PIAA lights attached and the luggage rack. </div></BLOCKQUOTE>

Marker lamps MIGHT cut down on some fuel economy since it is a wind restriction, but not that much.
Here is a thread I submitted last week on my fuel mileage I recorded on a trip. Vehicle had less than 1K when I left, and had only about 2200 when I returned. I expect it to go up as the engine breaks it, maximizing around 4-5K on the odometer.
The only speed limit I know is one where I drive safely, not what is posted. Average speed was around 73 mph per my GPS, but I hit 85 a few times, and I-65 through KY is not flat, especially when coming out of Louisville.
TN, believe it or not, is downhill out of KY, but still some rolling hills. Also some traffic through the larger cities.
As for the filter; K&N makes a lot of statements, and I never checked fuel mileage with one, but I can tell you from dyno'ing a Vette (and a few other Vettes on the same day owned by other people), K&N's statement about increased HP is BS.
As for exhaust, there is not that much restriction in the newer mufflers, and if all you did was setup to the rear of the resonator and the cat, you will not see much in the way of fuel economy over a stock muffler, and no increase in HP.
In the olden days, when mufflers were more restrictive, I would say a cat-back was a good investment. Now, it is more for looks and sound; and there is nothing wrong with that.
Good luck, and I sure hope you get your mileage figured out by a dealer.

[bparker]

Please take note, when you make changes to airflow - such as an intake or free flowing exhaust - you MUST - give the vehichle at least 500 miles to adjust the air/fuel mixtue to optimize results. As if you make a judgement before this it will be based off of a rich or lean condition.

[sharkman]

Good question. I drive about 75-80mph, give or take with the AC off. HUMMER claims I am driving too fast and this vehicle isn't meant for those kinds of speeds. How fast do you drive, typically?

I don't accelerate abruptly, either.

[sharkman]

I appreciate the input. I have put almost 4000 miles on the truck since the modifications.

[sharkman]

what mpg did you get on this trip, average?

[H3OH]

LOL! This is a funny thread.

Gas mileage is great for me. It's better than what my friends are getting with their SUV's.

As someone else mentioned, how heavy is your foot? Are you stomping it at the light? Manual or auto? Driving habits? Need more specifics to see what your "problem" is.

[sharkman]

My foot isn't heavy at all. I do tend to drive 75-80 on the freeway (which is what Hummer says is the problem). I traded in my YUKON XL for this truck and I haven't changed my driving habits at all. Ironically, the Yukon, with a 5.2L V8 got better gas mileage than this H3, with the 3.5L inline 5. I definitely don't accelerate at a light or stop signs. My H3 is an automatic.

[MyxH3]

Well I for one have a heavy foot and I have been averaging around 14-16 in the city and between 17-19 on the freeway,I average 75mph and have an automatic. I drive 50 miles each way to work and its a combination of city and highway. I am loving it I get alot better mileage than I did with my Xterra. Although that said i havent driven it loaded down yet but that is coming at the end of the month.

[f5fstop]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by bparker:
Please take note, when you make changes to airflow - such as an intake or free flowing exhaust - you MUST - give the vehichle at least 500 miles to adjust the air/fuel mixtue to optimize results. As if you make a judgement before this it will be based off of a rich or lean condition. </div></BLOCKQUOTE>

Air/fuel misture on the modern engines is almost instantaneous. The PCM constantly reads the O2 sensors, as well as the MAF sensor, air temp sensor, ect., it then computes the most optimum air/fuel ratio, and constantly changes this as you drive. Chaning the air filter or cat back exhaust will be sensed almost instantly by the computer. Besides, there is litte to no affect with these items in regard to air/fuel mixture.
The transmission has a learning capability, called adaptive strategy, that will adjust with driving over a period of time, usually within 50 miles.

Sharkman...
Explain to the dealer that many states have speed limits of 75 mph, and the vehicle is more than capable of driving at that speed. If some idiot at the dealer says the vehicle is not designed to drive the speed limits in many states, then they have to purchase the vehicle back. The vehicle is only governed by the speed rating on the tires. It won't even come close to redline at the governor speed.

jkH1+H2=H3
The off-road tires on the H3, which I have are not going to affect fuel mileage that much, if at all. The PCM is programmed for the larger tires. I would agree if I replaced my tires with 35 inch Mudders, but not with the stock off-road tires.

[jkH1+H2=H3]

Wow, you guys travel fast!!! Im getting at least 17mpg to 19mpg. I travel the highest @ 70mpg. One more speeding ticket, I go to Jail!!
Also, What tires are you Running. With the 33's, I was told that will drop down the MPG.
Logically speaking, its like riding a mountain bike vs. a Road Bike. A road bike will give you more mpg at a higher rate of speed. With MTB Tires on a Road is about 9 to 12 mpg. Road tires will Be @ 15 MPG up to as fast as you can pedal 24-30 MPG.
Also, Remember, the V5 engine is not a hole shot type of engine if your in motocross, OK, Slow, slow,, in the get go,
allow the engine to build speeed....
If you are Gunning it all the time, to go faster, everytime you gun it, Ching, ching, ching, glug, glug, glug, you want me to give you speed, give me your gas!!!!!!!!!!!!!!!

[mightypuck]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">sharkman
Hummer Novice
Posted 09-13-05 05:00 PM
Good question. I drive about 75-80mph, give or take with the AC off. HUMMER claims I am driving too fast and this vehicle isn't meant for those kinds of speeds. How fast do you drive, typically? </div></BLOCKQUOTE>
75-80mph...you have to drive that fast here in California or else you're going to get rear ended...by a semi, yep those damn 18 wheelers

[killian]

I'm not real sure that I care what kind of mileage I'm getting, I just enjoy driving my truck.

[bparker]

Yes, those are the short term fuel trims and they are changed for driving conditions - but they will not be correct until the long term fuel trim tables are updated after 500 miles - then and only then will the short term fuel trim tables be accurate and optimized.

Brent

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by f5fstop:
Air/fuel misture on the modern engines is almost instantaneous. The PCM constantly reads the O2 sensors, as well as the MAF sensor, air temp sensor, ect., it then computes the most optimum air/fuel ratio, and constantly changes this as you drive. Chaning the air filter or cat back exhaust will be sensed almost instantly by the computer. Besides, there is litte to no affect with these items in regard to air/fuel mixture.
The transmission has a learning capability, called adaptive strategy, that will adjust with driving over a period of time, usually within 50 miles. </div></BLOCKQUOTE>

[sharkman]

I drive exactly like you (45 miles each way to work) and a combo of city and freeway. The BEST MPG I have gotten is 14-15. That is why I am so frustrated: the H3 is supposed to get close to 19 and I am not anywhere near that. I keep telling Hummer there is an issue with this truck, but nobody seems to care.

[Sharkster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by killian:
I'm not real sure that I care what kind of mileage I'm getting, I just enjoy driving my truck. </div></BLOCKQUOTE>Same here too. I would only notice the mpg if it was at an extreme... (like e.g. in an H2), but otherwise I don't care. I had a Mercedes ML 320 before I got my H3 and I think it was subjectively at the same mpg consumption... but I never researched the mpg "in-depth".