Hummer H3 only getting 6-7mpg? What could be causing this?

Have not had the opportunity to "check the math", as I just purchased the vehicle. In the process of coin just that. It is a Hummer H3 3.7, and as noted, bc it's new to me, I can't honestly tell you if it's running ok. It seems to be? Driving conditions, we live in Houston TX, (not sure where the Potwin came from, must be repair pal auto fill).

Ok, Texas would make a little difference because of the terrain.... Check google for fuel mileage specs... Edmonds, KBB maybe.... It should do better than 6-7 mpg!!