Just like it is possible for SR+ and LR owners to go over the rated range by careful driving, it will be possible with this model as well. As such, you shouldn't base your understanding on reports of distance driven. At the very least, you should have all the information in that case: exact route (to know elevation), wind, temperature, speed travelled, weight carried, tire model, inflation...
Since we know it's a ~55kWh pack just like SR+, it has to be software limited. Using a constant of 148wh/km like the SR+ (it's the same weight etc) gives a usable capacity of 22.35kWh for 151km. I don't know if they keep a bottom buffer, and if it's usable like in other models, but clearly there's going to be a big top buffer. I would be led to think that filling to 100% (displayed) regularly would not be a problem all all. 22.35 / 55kWh does give 40% as shown in ScanMyTesla (or other app), which gives good credit to this theory that it's all top buffer.
Cool, this pretty much re-iterates my understanding, but obviously selling a car with an absolutely explicit range "limit", regardless of what the car is
technically capable of, has never really happened before.
A small part of the puzzle missing is an absolute confirmation that it charges based on some kind of nominal estimation of what "151km" is in actual kWh (22kWh?), but actually has a fairly flexible "limit". It seems to me that, as others have said, calculating available range on an essentially 40% use-case battery is incredibly difficult. Basically, it would be great if owners had some kind of accurate way to log the
actual ending SoC (the app?) and power used (tougher!).
Also, there was very little data of real-word range versus estimated range, a few tantalizing snippets, but very little to go on. Unfortunatley, the owners that did post semed to be more concerend with the after-charge estimated range, rather than what they actually experienced.
My guess is that it has to be some kind of baseline required charge for 151km (22kWh) and it tracks usage while driving and when you go to charge it simply charges the power that has been used, to try to reach that baseline, but also allowing for a bit of a fudge-factor if the displayed, estimated total range would be far above or below that. Obviously, the weird situation of having a fixed estimated range means that from a customer satisfaction point of view, you can never really have that fully-charged estimated range be much off the 151km "nominal", something like 120 would be a PR nightmare for them, so I assume there is a lot of futzing to make sure it stays in a +/- 10km window.
As has been noted, in the middle of winter it would still charge to 150-ish km, which seems to suggest that if it was -5C one day, the a next, a sunny spring day 15C the next, that sunny day you may have a far bigger "buffer" since the car actually put far more than 151km worth of "warm weather" power back into the battery. But, is that "buffer' usable? Good question!
If you think about it for a while, it's actually extremely complex when you look at driving situations and what the actual efficiency might be per 151km. It's a ginormous kluge, but I suspect that there's a lot of erring on the side of caution, which owners
might be able to leverage, under the right conditions.
