DrG, different H2s have different mpgs seemingly unrelated to location, altitude, a/c on/off, etc. I tried driving for a month "gingerly" with a/c 90% off, and my mpg only goes up from 10.4 to 10.8. Others have always average in the 12s (or like Tower, in the 9s). Don't give mpg another thought.
And if you think you're already having "GREAT FUN!" now, you're gonna have aching jaws when offroading, from grinning so much..
Have fun tommorow!