It confuses the heck out of me. I start full EV and drive close to a mile (still have over half battery) and the thing gives me 3 bars 67! Then I can start from a dead stop and get up in the power red range going up a hill and all....and get 5 bars!!! Damn thing! haha, it all good and fun though. 5/4/5 with a 97 is the highest I got.
I actually don't drive with the eco score anymore. I like the screen that shows where the energy is going, or coming from. My confusion with the eco score was that I usually seemed to average between 80 and 90, but was getting over 70mpg at the same time. Then my father drives my car once, drives it with a lead foot for around twenty miles, barely gets 54mpg, yet he pulled off a score of 95!?!? He was super proud of his score of 95, but I couldn't get past his "lousy" 54mpg. I even drove the car back, using the same route, pulled off an amazing 77.2mpg and only got an eco score of 83?!?! I gave up on it after that and haven't looked back.
Even the manual states that Eco score does not necessarily correlate with mpg results. I focus on the mpgs, and look at the Eco score more for fun, without really trying to get good scores.