This may help everyone, this is Tesla's official response that I had got from them. In short, the 90% charge is going to reflect the algo learning how you drive, so its going to be different for everyone and likely seasonal as well. If you drive harder, or in less ideal conditions, etc then seems as though it will learn and you'll get less than others' 90% versus starting at the same and just losing miles faster.
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The original 240 miles (for 70D) is based on a test of the vehicle’s driving efficiency in ideal driving conditions. Clear sky, no traffic, 60-65 MPH. As the vehicle is exposed to your various driving conditions which can allow efficiency to falter from time to time, the vehicle will soon adapt to the conditions and display a more accurate or real-time estimate of miles based on that history.
Essentially the vehicle’s algorithm that projects usable range has learned your driving conditions/style and thus the apparent loss of range. You should continue to feel confident in your vehicles battery as regardless of what may happen over time you are covered for 8 years Unlimited miles if there is something that comes up with the Battery.
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