Elevation and Mileage

[Gunzz]

Hey folks have a question that I hope someone can give me some insight on. First I am driving a 05 H2 and the only performance mod is a re calibrated computer. This was done with a Diablo Predator unit using the 87 octane setting.

Now here is my question. Recently we took a trip to the Pocono mountains. (Probably only 1500' elevation). During this trip I was averaging 15, YES 15 mpg in the mountains. As soon as I returned home (New Jersey near the shore) I went to back to my average 12.5 to 13 mpg. Of course this is driving conservatively. Weather, and temp is the same. So my question is why was I getting 15 up there, way above what I normally get? Do you think it is only because in the mountains you can do alot of coasting downhill? My thinking is that you also have to drive up hill alot also so that wouldn't be the reason.

I have repeated everything (no A/c, same weight, same passengers, same temps, same gas and full tank) and cannot duplicate. Someone give me some insight please.

Thanks Mike