I have had my 2007 I5, H3 for about a month now. Its stock everything as far as I can tell with 265 stock tires. With 100% street driving I'm getting 12 - 12.3 MPG. Is this normal or is something wrong here?

 

20 on turnpike,last trip

are you in drive,,overdrive?? is it shifting to od? thats about 30%

brakes dragging?,,i check by shift to neutral on slope. it should move freely,immediatly

you got a heavy foot??

 

Dude, even when I was stuck in a mud hole for 4 hours trying to get out I still got like 12.x mpg I think. I get 19.2mpg bone STOCK, STOCK air filter and everything, on the highway. City driving is 16-17mpg.

 

I drive it like an old lady. Maybe the previous owner put a chip in it or something? I just better take it to the dealer and let them give her the once over.

 

Wow really? Because I drive like an old lady too. I NEVER shift above 2200rpms, and when I take off I'm usually neck-and-neck with the 18wheelers alongside me until I get up to speed. I only go 6-7mph over the limit max, and thats where I get my 19.2mpg from.

 

Someone had a problem with a clogged catalytic converter causing bad MPG

 

You do have the Parking Brake off, dont you?

 

are you measuring your mpg correctly?

 

and one more comment . . .
I get about 20 MPG of the highway with my unmodified 5 speed 07 H3
Around town is about 18 MPG or so.
Driving styles has a lot to do with mileage
I see people literally drag off from a green light like it were a christmas tree
light at Pamona. Then those same people complain about lousy gas mileage.
All the above suggestions are good and it should get better milage than 12 MPG
Check your vehicle over carefully

 

^^This is true. If you are racing your 5,000lb HUMMER around like it's an indy car, then yes that gas is going to be sucked hardcore.