The wh / mile constant has nothing to do with the battery.
Kinda. The wh/mi is a constant based on the battery/motor/chassis combo. Change any of those, and you change the constant. Obviously not the case here, though, just nitpicking. lol.
@wk057 , Do you agree that regardless of the reason, Tesla's latest software is removing access to capacity that actually exists?
Yes, the capacity definitely exists. This isn't a voltage-based limitation like what happens with an SoC imbalance (like when a module has cell-fused failed, or otherwise is degraded in a non-uniform way). In that case, the pack can't physically be charged beyond the limit because it would push some cells over a safe voltage.
In this case, there is no physical limitation and the pack can still be charged to the original pre-update capacity. I've fully confirmed this with the NVRAM reset of my one client's BMS, which is happily charging to right around his original 100% capacity right now.
Additionally, do you think when Tesla did this and say cut the SOC to say 85% of existing capacity that they indicate 100% SOC when it's only 85% or do you think they should display the true SOC and indicate that they will not charge above that?
The BMS uses the lowest of all available capacity variables as the max capacity used for SoC. In this case, the SoC being used is determined by the new unknown variable that's being calculated, since it's the lowest. So, the car will report 100% charge at this capacity.
Again, I do believe they've done this to head off a safety issue. And they need to make good with customers one way or another. They can start by being clear about what the issue is.