I don't look at my Android phone when I'm driving. I let the GPS lady who lives inside my phone read off the turn-by-turn directions for me.
I would not take my eyes off the road to look at any screen--4 inches, 7 inches, or 20 inches--while I was driving, nor would I read a paper map while driving. Flying is usually a little more forgiving about letting you look at things inside the cockpit for a few seconds at a time.