I guess I'm flabbergasted by this, as that's not how my Chevy Volt (and I presume many other BEVs) work. The range value ('guessimeter' people call it) on my Volt takes something like a rolling average of your last few drives and that's what it shows you. So if it's winter, it shows you less range because your last few drives had less efficiency. It's not always accurate (if there's, say, major temp fluctuations), but it's way more useful than what you're describing.

To me, what you're describing is border line dishonest marketing, and technically unnecessary.

What I'd like to see is two numbers: estimated range as I've described, and beside it a kWh # (which I can guesstimate from the battery % gauge visual, but not precise).