Some data on charging a Tesla 3 Long Range. The owner pulled into the 250 kW Supercharger with 10 miles of range left. 2%. When charging started the car's range gained 6 miles of range in the first minute. Those are the first two data points in the table below.
Those timings are interesting because they actually run contra to the cell manufacturers guidelines on charging times for the cells.
Also, according to the manufacturers guidelines, if you charge 40% to 90%, you get thousands of recharges. If you charge 2% to 90% you will get somewhere less than 1,500 and, in certain cases, less than 1,000, before the battery starts to degrade.
These are not surmises, they are the manufacturers stated cycle guides before degradation sets in.
I'd love to know how they have achieved this as the manufacturers guide states the cells can't take the rate of charge as they approach 90% and even less over 90%. Somewhere, long back in this thread, is a video of a Model3 and the time it takes to charge it. Granted not on a 250kw charger, but, then again, it was not drawing the full power of the charger later in the cycle so 250kw should not make any difference.
As for the 80/20, you are assuming availability of superchargers and, even then, you are assuming that everyone wants to drive right down to low % levels before charging. My wife regularly drives from France to the UK, the nearest superchargers, on the route, are well over 300 miles from our home in France. My wife also says she doesn't want to stop, in the middle of the night, at a place she does not know, in order to "fill up". She doesn't need some whacky hybrid car, her Citroen C8 7 seater MPV has an average range of around 700 miles, driven around 70mph, some 650 miles when driven around 80,mph. She can get to any of the French ports with that range.
There are significant numbers of people who travel quite a distance on holiday, tow on holiday and even caravan on weekends or for short breaks. Seen any caravan charging points? I haven't. You'd need to drop the caravan, charge up and then hitch up again before moving on.
On the driving side, I have driven well over 1,000 miles in a single hop several times and twice I've driven 1,500 miles in a 24 hour period. Granted I slept in the car for 2-3 hours during that time. However that is only one charging stop if you see it that way. Over and above that, it included extended periods of high speed cruising on the Autobahn (over 100mph for significant periods, 100-125mph for shorter periods as the engine didn't like it).
Judging by the way my C8 dropped MPG towing two of my motorcycles on a trailer, my journey form the UK to France would have necessitated at least 3-4 charging stops. In my C8 it was a single hop although I did reduce the range from 700 miles to just over 500 miles when towing. You can see the impact it would have on a Tesla.
I don't believe that my "20%" is quite so far from reality. The problem is that current EV purchases are low hanging fruit from the 80%. The noise comes from those it won't suit today.
LOVE to know how they get around the 45 minute charge time for the cells to 90% though...
