Just to understand, you are not using the function to get you from point A to point B but just to give you an on-going map as if you put point A to point B (you don't want directions in other words). Or is the function you are looking for something different?
Basically, what I want is for it to follow my route as I'm driving, (as if I entered Point A/B) and auto-scroll the screen. As I said, I tried it this morning. I brought up Google Nav, selected Directions, then backed out of the directions entry screen without entering any data. The indicator (little blue pointer) would follow my position (very accurately, I might add), but the screen would not auto-scroll as the pointer reached the edge of the current screen. The pointer would just disappear off-screen and I would have to scroll the screen manually with my finger.