I don't think this is necessarily true. For instance, there is no way that I experienced 4% degradation 5 months and 7,000 miles after doing my first 100% charge in March. I have a B pack. When I max charged a few days ago, the display showed 289 miles but the car continued charging for a good 30-40 minutes after it hit 100%. That current went into the pack even though the miles didn't increase beyond 289, so there is more charged capacity than the display is showing. The first time I max charged in March, I could drive 11 freeway miles before the display dropped by 1 mile. After max charging a few days ago, I immediately lost range as soon as I started driving.
The algorithm seems to be pretty wonky and unreliable when it comes to determining actual pack capacity.
You need to watch number of kW during charging. That final 40 min on range charge is balancing and it is charging at very, very low rate. Algorithm has clearly changed over firmware releases but is not wonky!
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This is consistent for me. 18 k mi, A pack, 100% charge is 250 to 260 EPA rated. Not far off the original 265.At 24,000 miles and 2 years, on the original A pack, I get 255 range miles on a 100% charge. If I do a few 100% charge, more than 50% discharge cycles on a trip, I can occasionally see 256 range miles.