2009 H2 gas mileage improvement?

[sharkman]

I own a 2009 H2 and the gas mileage SUCKS! I replaced my 2006 H2 with this one under the premise that with the larger engine and 6-speed transmisson, the gas mileage would improve by .7mpg (according to the dealer). I was getting about 13-14mpg on the 06 H2. What did I have to lose: larger engine, redesigned interior, smoother ride, better gas mileage.....

What a laugh. Right now, I get 10-12 mpg, going downhill with the wind at my back. AND, the manual says I need to use Premium gasoline.

What mods has anybody installed (that are relatively inexpensive) that have improved gas mileage?

[seventwozero]

Stock size tires? How many miles are on the truck? It's possible it uses a little more gas till the motor is broken in.

[sharkman]

Originally Posted by seventwozero

Stock size tires? How many miles are on the truck? It's possible it uses a little more gas till the motor is broken in.

good questions: Yes, the tires are the stock 20" that came on the vehicle from the factory. The milage is 16000. I haven't done any mods to the vehicle.

[H200]

Have you taken it back to the dealer and told them it isn't living up to their claims on gas mileage?

[sharkman]

Originally Posted by H200

Have you taken it back to the dealer and told them it isn't living up to their claims on gas mileage?

yes, and i have called Hummer customer service. they claim that's just the way it is.

There must be SOMETHING somebody has done to the Hummers to help increase milage.

[Olfart]

for highway driving running 40psi in the tires should give you a couple of mpg. It did on my 2004.

[Hellz]

this should be fun to watch...

[Xotik H3]

Larger enginer and 6 speed tranmission will give you better gas mileage

I run 42 psi in my 03 and did improve 1 MPG on the freeway.

[mikejr]

I am getting 11 MPG per the DIC in my 09 LE. Its not any better than my 06 or 08 was. I do burn premium fuel since the regular just doesnt run right in it.

There isnt much one can do to make a 4 ton brick get good mileage. Its just the fact of life when you own a Hummer.

[sharkman]

what about a cold air intake system? they are like $400-$500 from K&N. Is it worth the money. Maybe since i drive 75 mph most of the time, it just is what it is.....Yeah - I know, slow down. ain't gunna happen. you go slower than that in LA and you get run over.

[MVR 155]

I have a hard time believing you were getting 13-14 mpg's with your previous rig (unless that was all highway).... were those real numbers or is that what the DIC was reading? Coming out of a 2006 to a 2008 I can say that we get a solid .5-1mpg better with our 2008 around town, have not driven any real highway trips to speak of but on a tank with a good amount of highway driving I did see nearly 13mpg's. There is no doubt in my mind that the 2008 with the 6 speed will do considerably better on a road trip in terms of mileage. The best I ever did with the 2006 was a bit better than 14mpgs on my way to Florida in it last year (the rest of the fill ups netted anywhere from high 12's to just shy of 14) and I was being very concious of my driving style trying to get the best MPG's. I honestly feel I could get a solid 14-15 with the 2008 on the road based on what I have seen from the limited amount we have driven it.

One last question.... since your 2009 is Flex fuel are you running regular unleaded or E85? If you are running E85 then that is where your mileage is going.... E85 nets less mileage than regular unleaded fuel.

[sharkman]

Originally Posted by MVR 155

I have a hard time believing you were getting 13-14 mpg's with your previous rig (unless that was all highway).... were those real numbers or is that what the DIC was reading?

One last question.... since your 2009 is Flex fuel are you running regular unleaded or E85? If you are running E85 then that is where your mileage is going.... E85 nets less mileage than regular unleaded fuel.

Yes, that was 90% highway mileage. I do very little in the city. I use Premium Unleaded Fuel - NOT E85.

I guess one of the keys is slowing down, but that ain't gunna happen anytime soon.

[HUMMERICH23]

I average 14-15mpg easy in my 08 H2. Right now my cpu reads 14.0 mpg with a range of 448 miles when i fill up. During winter I usually drop down to 12.5-13 easy. I have gotten 18 +mpg Highway easy especially when doing the speed limit. If I go 55-60 i get 18.5-19ish, 65-70 i get 17ish, 70-75 i get 15-16mpg. At 80 it is terrible, drops to 13-14. I do mixed city highway and it’s my daily driver. i haven’t reset my mpg avg since spring and like I said its at 14.0

Have you reset you avg mpg by holding check mark button down after you have gotten to cruising speed and see what is says? Try that doing different speeds to see what your truck is capable of. I know you prob can’t go any speed below 75-80 since you’re in socal but if you could try it doing 60-65, 65-70, etc. I absolutely love my 08 with the 6.2 and 6speed and wouldn’t have it any other way.

p.s. I do have Air Intake, Performance Exhaust, and CPU Tune mods. I have had those since pretty much it was brand new so I can’t comment on how it runs without those mods (sorry). I only use 93 octane and in general the 6.2L runs much much better with premium
(most of the numbers too i gave you are on flat straights, not many hills or mountains around here)

[sharkman]

Originally Posted by HUMMERICH23

I do have Air Intake, Performance Exhaust, and CPU Tune mods.

What brands did you install?

[HUMMERICH23]

GM performance Parts air intake, Corsa Sport Cat Back Performance Exhaust, Westers Tuners 93 Hot tune

[Xotik H3]

Originally Posted by HUMMERICH23

GM performance Parts air intake, Corsa Sport Cat Back Performance Exhaust, Westers Tuners 93 Hot tune

At least it will sound better while giving you a .5 increase in mpg.

[vetteSUT]

Premium burns better.... aka burns faster. Stick with 87

[MVR 155]

Originally Posted by vetteSUT

Premium burns better.... aka burns faster. Stick with 87

This is actually false, higher octane is more resistant to pre-ignition/detonation and actually burns slower.

[Stellar]

90% of my driving is highway. Avg 15.5 - 16 mpg @ 70 mph..
Royal Purple Synthetics
Airraid Air Filter
160 thermostat
Throttle Body Bypass
Tires at 50 psi