There are several threads on the matter here:
I may be wrong in my assessment, I'm not from the USA, but my conclusions from reading many similar complaints here and on FB group so far are as follows:
- BMW have a standard testing procedure how to verify the capacity of the battery pack. It's there in the menu of ISTA+ (the service software), several people in this forum performed this test at their dealers. Under this procedure the pack is charged to 100% and then fully discharged using climate with windows open. ISTA+ seems to register the available capacity, allegedly.
- No detailed outcomes of the test are usually provided, they just say the battery is OK. Sometimes they apply some magic, and the pack miraculously adds several kWhs to its Batt.Kapa reading. Overall, they do their best to obscure the procedure.
- Given significant variability of the available range and even pack's capacity depending on the ambient temperature, charging patterns, driving style, cell balancing condition, owner affiliations and whatnot, it's quite easy to dismiss any claims by owners that something is wrong with the battery. So, no wonder they do that. They'll employ red herring tactics until there's a class action lawsuit or something like Nissan experienced with their Leaf.
Please report your further steps and experience going forward, it's very interesting.