Sorry this is not more clear.
My cars display of full charge range (275 miles) is only consistent with a battery which has more capacity than my battery has. For the amount of battery degradation that my battery has, the display of full charge range should be lower. If I drive at the rated wh/mile, I will not get the rated range displayed (220 instead of 275). Not even close. Bottom line: My cars display of full charge range is just plain wrong. By any measure. Since the displayed full charge range is inaccurately high, it gives the false impression of a battery with less degradation than my battery actually has.
Of course it is true that if I drove with a low enough wh/mile, I could get the rated range as displayed. But if the wh/mi necessary to achieve this (277) is both unattainably low, and lower than all published values (300-330), then it is a fictional contrivance.
For years, the vast majority of owners have assumed that full charge range displayed is an accurate reflection of battery condition. While that may be true for many cars, it is certainly not true for my car and others. Thus, the displayed full charge range is not in general a reliable indication of battery condition. Of usable capacity. Many owners are loathe to believe this. But it's true.