Another look at energy use VS. speed - from the internal combustion world.
This chart is compiled from data collected by hundreds of VW diesel drivers that are part of tdiclub.com.
The first thing to point out is that it's 'upside down' compared with the Tesla watt hour per mile chart because it's a 'miles per unit of energy' chart instead of a 'unit of energy per mile' chart. Notice that the highest fuel economy for a range of different models (Jetta, Golf, Beetle, Passat have different colors) happens at 35mph?
While the absolute fuel economy - energy per mile - changes from a bit over 60 to 90 miles per gallon, the speed for highest economy (lowest energy use) happens at the same speed - regardless of vehicle size, drag, or weight.
When an EV manufacturer says a car gets best range at 35 they're simply reflecting the laws of physics, not necessarily a misguided marketing department. It's common for electric scooter manufacturers, for example, to give a 'max range' number, and a 'max speed' number. The max range will happen at about 35 mph - and unless one has a downhill commute both ways
they'll not get that same range at 55mph.
Just like with a gas car - if you need to get another 10 miles out of the 'tank' to make that fuel station, turn off the AC, slow down, and crank-up your hypermiling skillz.
Andy