Hey guys, I've been getting terrible gas mileage on my first two tanks on my H3. My first tank I got around 11-12 and this tank I got around 10-11. Is this normal, or is it because the car isn't broken in yet? I've been doing normal speeds with slight acceleration, staying around 65-70mph. A lot of it has also been highway driving around 25-30 miles at a clip. Let me know your guys take on this.

Thank you again!

Oh the reason I say this, is because the salesman told me his son has the same truck and he gets over 20mpg driving on the highway.

Oh and yes I read https://www.hummerforums.com/m_47096/tm.htm , I just wanted to hear people's personal opinions about my scenario.

 

I just went from Georgia to Louisiana and backdoing 75mph most of the way and got around 20mpg.

 

I getaround 18 on the hwy doing between 70-80. 10k miles on my 07 H3, one year old today!

 

my first few tanks i also got crappy mileage, between 10 and 13. now i have 4500 miles on it and i can get 20 on the highway and averaging 16-17 with city and highway combined. just give it time to break in.

 

I have 3,350 on my H3 and I have averaged over the past 4 fill ups of 14.3 mpg mostly city driving and 17.3 highway.

 

My H3 didn't break in until about 4000 miles. It suddenly zoomed from 15-16 mpg on the highway to 18-19. Give it some time.

 

My new (just over 1 month) H3 has gotten 15.51 and 14.54 MPG on the first two tanks. I still have less than 600 miles on my vehicle. First tank was a little more highway (almost 100 miles driving home from the dealer) and the second tank was more local driving. Kept it at 55 or under until I broke 500 miles (I know-I didn't "drive it like I stole it". )

 

Did anyone notice any MPG increases after a tune, CAI or improved exhaust?(duals)

 

It's going to take a bit for your engine to adjust so getting bad mileage at the beginning is normal. You aren't supposed to be driving on the highway during the break-in period so that could have alot to do with it.

I get better mileage after I has PCMforLess tune my PCM. Anything over 65 and your mileage will start to suffer normally with most people on here at least. I wouldn't worry about it until you put a few thousand miles on it. If it still suffers, then you need to get it checked out.

 

Thanks guys. I was just astonished to see only 250 miles in one 23 gallon tank. I just refillled and I'm going to try to drive more aware of my acceleration and what not to see if its me thats sucking the gas out of my truck . Anyway, I'll let you guys know the results. Thanks again. And Also HummerGuy what type of difference in gas mileage did you get with the PCMforLess tune? I was looking into that