Ok peeps...this is crazy. We drove from Gainesville to Miami (330+ miles). We filled up in Gainesville before we left and started our trip-ometer. When we refueled againwe had gone 287 miles. After putting in 19 or so gallons of gas, we did the math....around 14 MPG!!! That is highway driving...not even city. Does anyone else keep up with their MPG? I didn't buy the truck to save gas, I bought it for the comfort, but Hummer claims the H3 will get 16 city - 19 Hwy.
Any suggestions to get better MPG? We have the roof rack and overhead trim lights with the grill guard (maybe it's the extra weight?). We also have a K&N air filter, due to the fact it gave us an extra 10 MPG on our old BMW. We only had 2 gym bags full of clothes, so we didn't have her weighted down with lots of luggage.
It is the H3X with the tire carrier, all chrome acessories, with running boards and roof racks. The dealer recently did a computer update (in the last 3000 miles) due to needing a replacing the fuel tank and intake lines. We used the fuel injector cleaner from GM when we bought the truck (36,000 miles on it) because we didn't know what the old owner used to do with it. The truck only has 46,000 miles on it now.
The owner's manual says you don't need to replace the spark plugs/wires until 100,000.
PLEASE HELP!!!!!

 

Alot has to do driving style, how fast your going & accelerate, the EPA data is based on 60mph I think, so if your going faster your mpg will drop. I just did a 3000+ mile trip & at around 80+mph I was getting the same as you, if I dropped down to 70-75 I was getting 18-20mpg & at 65 I was getting around 22mpg. I have done the PCM tune & air intake upgrade which are supposed to help but I tend to have a heavy foot on the gas & can't stand doing less than 80mph on the highway.

 

Yeah, that's about right....we were constantly at 80+ and then slowing down for the elders doing 60 then getting up to 85 again makes sense. I guess next time we'll set the cruise control at 75 instead of 85! = ) It's pretty bad when city driving in Miami was also at 14 MPG! Like I said, I bought her to cruise not for gas savings! Not complaining, just wondering if it was the computer update the GM dealer did, or not. Luckily we don't drive her too often and can afford to put gas in her! So far I think she is the BEST vehicle I've ever owned (previously 99 328i BMW, 00 Chysler 300M, 96 Ford Explorer, 96 GMC Sonoma)!!

 

Man I have only dreamed of getting 14mpg on the highway. With The lift, 37" tires and a roof rack I struggle to get 10mpg. lol. Before all that I used to get close to 13MPG on the highway. And the there is towing the boat. That usually warrants 7.7MPG over a 100 mile somewhat hilly round trip lol.

 

WOW, was there an old towel stuffed in where the air cleaner should have been???
Pretty unbelieveble!

 

I tend to run around 75 on the highway, resulting in around 17mpg.

If you really want to become aware of what your driving style gets you in mileage, add a ScanGuage II or similar. That lets you see your instantaneous MPG and cumulative MPG for the tankful. It may not help but you will know what's going on.

 

thanks everyone for all your advice here. if anyone wants Direct TV i have some employee discount cards left which will save you lots of money plus that NFL ticket right now. every game in the US is played on TV. if anyone wants the coupons please let me know and ill send you all the info you need. my way of paying back all the help i have been getting here. plus with this employee discount you get a free DVR its like Tivo. let me know and ill hook you up email me fishin301@yahoo.com. thanks again

 

Well - I went and made sure ALL the tire pressure was good (30 PSI according to the door), we started using mid-grade fuel, and started setting the cruise control @ 75 MPH on the highway...so far we have gotten 16 MPG....so a little better, but not worth mentioning....i guess that's 16 city though, since we don't drive on the interstate much....lost of Football traffic lately...luckily we only fill up every 2 weeks! Thanks for all the suggestions...they all seem to help. I now pull out in front of people and go pretty slow...it's a HUMMER not a BMW!!! = ) I bought it to be seen, not to out run!

 

It's not likely the weight of your accessories but their aerodynamics or lack of. On another forum a poster reported getting 2 more mpg by simply removing the crossbars on his factory roof rails. I get 1 to 1.5 better mpg myself highway driving doing the same thing. It's a combination of things as other poster's have said. I would guess if you removed the accessories and slowed down to 70 you would get 19 or better. I also get better mpg using gasoline without 10% ethonal.

 

sorry 20 mpg is utter bull. city i get around 13mpg if im lucky. upto 16-17 with cruise control going 40mph on highway. 20 is a imaginary fantasy number.