Thanks to Teslafi.com I have data from my car for the last 80k miles. A new feature they added recently is the 'battery report'. It shows the rated range over time thus giving you a great way to see your battery degradation. Here is a screen shot of my car. It's a 4 year old Model s 85 with 160k miles. This graph represents roughly 2 years (when I started using Teslafi.com) The blue lines is the rated range reported by the car from 85k to 160k miles on the ODO meter. It's a little noisy but that's expected. The gray dotted line is just a straight from start to end. The black line is what I added showing the trend the way I would see it. Clearly there is a point where the range drops faster than it did before. I manually recorded data from the first two years of my car. When extrapolating the curve in this graph to the beginning of my car's life it approximately matches the black line before the sudden drop. In other words, over the life of my car, the range dropped at approximately at the same rate (I excluded the first 10k miles where initial degradation is fast). Looking at that I'm a little concerned that after a certain amount of miles or time, degradation starts to accelerate. Kind of like an S curve. Fast in the beginning, then slowing down, and then accelerating again. It is not a temporary artifact or noise. The point where it started to accelerate is 10 months and 33k miles ago. Definitely a long enough period to not be noise in the data. I tried to find other correlations like temperature or other factors but nothing stands out or coincides with the point where it starts to drop faster. Any thoughts?