BMW 2002's have great visibility. Many call it the "fishbowl".
The stock rear view mirror is a bit small however and doesn't allow you see out of the entire back window. Most modern cars have larger rear mirrors than these so you really notice the small mirror in this car.
Easy fix. Find any later model BMW and you should find a mirror that will pop right on the stock ball socket of the 2002. Here are a few I picked up in my search, from bottom to top:
2. '82 320i
3. '77 320i
4. Stock 2002
As you can see, take your pick of size and go with it.
They all can be carefully snapped into place on the stock lever. The '77 lever is identical to the 2002 while later 320i levers are different and may need to be shaved down to fit.