Nice idea. I’m in the habit of watching for wheels to start rolling when I’m worried someone will unexpectedly pull out in front of me. A brake light is easier to see. Another scenario is an oncoming car braking which could help notice an animal entering the road or that the car has lost control ahead of you (sudden ice, for example.) Why green instead of red? Would it be an inverse brake light (green appears when fo…
A trick I learned years ago from a motorcyclist: pay attention to the front wheels of cars near you in traffic.
Very often, the front wheel turning is the first noticeable visual indication that a car is changing lanes or turning. That gives you a few more fractions of a second in a situation where they could be very important.
After a while, I noticed that I was instinctually able to tell more accurately if a car is accelerating or decelerating. After considering it, I realized that I actually could tell better than before, but it wasn't instinct. Because I was watching cars' front wheel, I was able to see the front suspension load and unload as they accelerated or braked respectively. It was just subconscious.