With an 80cc (66) you can pretty much scale anything that a car can, just slows down a bit.
The 48 you need to kinda help it on the really steep hills, or sometimes on dirt. But the 1-speed is more than sufficient. What I do is drive in a criss-cross pattern and the bike seems to take it better (trick I picked up from my Goped). Of course, a mirror helps for cars.