My Toyota RAV4 Hybrid provides a distance to empty number that "learns" based on your driving habits (probably just averaging your MPG over the last 3-4 tanks, or something like that) and IME at least it's usually extremely accurate. Several times I've driven the car down to just 5-6 miles left on the DTE. When I did that it took almost exactly 12.5 gallons to fill up, and the car has a 14.5 gallon tank with 2 gallons held in reserve.

If Toyota can manage do it, I'm pretty sure that Tesla can. I'm just not sure that they want to.