Wow, i didn't know about the difference between 4WD and AWD, i thought they were just different names for the same thing.
Anyways, i don't think we will do anything extreme, in fact in Iceland they have the Ring-Road (national highway) and mountain roads, called F-Roads (surface of loose gravel, small rivers with no bridges etc). By law, regular cars are not allowed on the F-Roads, but the Durango is of the type allowed, at least that's what the rental company told us, so i think it will be enough for us.

Thanks anyways!