Model S cruises at approximately 300Wh/mi; Tesla is claiming 2kWh/mi (approximately 6.6x the power consumption) for the Semi.
Diesel cars are rated at approximately 35mpg and diesel semi trucks at approximately 5mpg, a similar 7x factor.
So, yes in fact as the driver of an EV with an energy meter, I do 100% believe the 2kWh/mile number.
What I'm actually skeptical of and where I believe Tesla is burying the bad numbers is with the $/cargo ton/mile rating. Carrying an extra 8 tons of battery is going to limit the types of loads where an electric semi mikes sense.
Tesla claims the Semi is only 1/2 ton heavier than a typical tractor, not sure where you got the 8 tons figure from…
2 kWh/m seems plausible for level terrain for a larger vehicle that is presumably optimized for low rolling resistance. It sounds a little optimistic but not by more than a factor of two.
So my answer is yes I can believe it or something close.
If a truck is using 2 kWh/mile while traveling down highway at 70 miles per hour, its power draw will be 140 kW -- that is the one to compare to your 2 kW idling or 24 kW hard pull.
My EV uses 0.2 to 0.3 kWh/mile, so 2 kWh/mile for a truck seems plausible to me.
So 2kWh/mi = 120kWh/60mi.
But yes 2 kW is very low power. Around 2.7 horse power. Which is very little at highway speed. Specially with drag of any semi-truck.
To people without EVs, at 2KW in your car is idling forward from a stop. When you press the gas at a normal street at a normal start, you’ll be at 10-18KW/h until you are up to speed. A hard pull is 24KW/h, and on the highway I would assume 4-6KW/h in a light unloaded vehicle. So maybe they had some new amazing Tesla transmissions and Tesla low friction tires too?
EDIT: yes, obviously I’m talking about KWh instantaneous. So /second/minute/hour for the short frame until the next update. If you were to hold this power for the end of time you would use xx KW in an hour. Which is useful for the feeling of torque I described.