The Model S is not a good comparison to the Bolt EV in this case. The slope of that line is dictated by the aerodynamic drag force. The Bolt EV coefficient of drag is 33% higher than the Model S and so the line will be much steeper. At 90 mph steady cruising, the Bolt EV energy usage is probably 2-3x the average during the EPA test. 100 mi might not be possible.
Agreed. If you look at the EPA ratings, Teslas are actually rated higher (MPGe and range) on the Hwy cycle than the city cycle. Every other EV (that I know of) has lower hwy numbers. Drag functions in an inverse squared relationship - going twice as fast requires 4 times the energy.
There are several things in that article that raise some questions.
1) Teslas EPA ratings are based on the EPA 2-cycle test, not the 5 cycle indicated in the article.
http://www.fueleconomy.gov/feg/epadata/16data.zip
Select the "EV" sheet and look at column "BU". BMW, BYD and Nissan use the 5 cycle test. Everyone else uses the 2 cycle test
2) The graph seems to be unrelated to the EPA range rating and generated by some other means. They may very well be raw data at a steady cruising speed. The EPA hwy rating is a variable speed test and the results are then "adjusted". If the 2 cycle test is used, the results are derated by 30% (multiplied by .7) to better reflect real world results.
While the relationship in the posted graph is correct (range at 40 mph is double that at 80 mph), the numbers are not the EPA hwy range of the Model S.