This directly conflicts with something that I was told by the Tesla service hotline and, conversely, I believe now, confusion is the order of the day (or night).
Here goes.
As I understand it currently, the displayed range is in fact what is called "Rated Range" which is a calculation of range used by the car that looks at current battery capacity and divides that by a static EPA-derived wh/mi (which folks seem to think is around 242 wh/mi). So, a fully healthy battery at 75kw = 75,000 watts, so 75,000 / 242 = 310, just about.
And so it would seem to me that the Rated Range equation apparently looks like this for L/R Model 3's:
75,000 w
------------ = Rated Range (310 - actually 309.9 but rounded up)
242 wh/mi
With the denominator of 242 wh/mi being a constant, nothing can change this number in the equation - Tesla ignores actual wh/mi used in calculating this Rated Range number that is displayed. This means it matters not one whit how you drive the car, how much AC you're blasting, etc. Even if you're at 350wh/mi ave consumption, the Rated Range calculation still uses 242 wh/mi as the denominator, always always always.
But . . . . the numerator, the capacity, the 75,000w, now that *can* change. In these ways:
(1)
Temperature: Temperature can affect the displayed rated range number because colder temps change the numerator of the equation, the 75kwh number. When it's cold (like really cold, not like "oooh it's 65 degrees" cold) the capacity of the battery can decrease. Affecting capacity of the battery means when the car looks at (or measures) the capacity of the battery, in cold temps that numerator is less than 75,000. So now it's using a lower total capacity number to use against the still-static EPA 242 wh/mi denominator number. Result is a lower displayed rated range.
(2)
Actual Degradation of the battery Pack: If the pack's actual capacity literally does degrade, then again that numerator number of 75,000 w goes down, and rated range goes down as a result. The question then becomes - is that degradation at a normal or abnormal rate/amount, for the current life of the battery.
(3)
Out-Of-Balance Battery Pack: Folks say, a lot on the forums, that battery packs for these cars can come "out of balance". Not sure exactly what that means, or how that works, but the recommendation is to "re-balance" your pack by depleting down to 10% SOC and then charging up to 100% SOC. That might result in the capacity number going up, apparently. It did, for mine, a little, but within a week, that was gone, and I'm down to 288 miles rated range, lower than ever.
(4)
Bad Pack: A bad battery pack! If you're losing too many cells, or if otherwise the pack is losing capacity unsusaully for whatever reason, I'd call that a "bad pack"! Bad pack; please may I have a new one . . . .
Anyway. This represents a summary of what I've come to learn on the various forums. Feel free to find fault with it, and let me know same. I'm here to learn/understand; not here to defend a position or opinion that doesn't make sense . . . . .
Something like that.
PS - I'll post something more about this after I have my car looked at by the Dublin SC late next week. Maybe the Tesla technicians will set me straight if I need that, or confirm some/all of my current understanding.