This has nothing to do with Prius, Leaf, or Tesla. This is about on-the-ground EV enthusiasts’ work.
Up until a few years ago, electric motors were lucky to get 40% efficiency. That is, of 100% of the charge in the battery pack, the motor was only able to use 40% of that energy, the rest being lost to heat, mechanical friction, and the “cogging” effect of newer neodymium-magnet motors. So for a given range, you needed to include 60% more batteries than you would if efficiency were 100%.