Actually, elevation makes a big range difference, especially at higher speeds. Total aerodynamic drag force proportional to drag coefficient x frontal area x air density x velocity squared. At 70 mph, aero drag is 60% of the Hummer's total "road load" horsepower. Rolling resistance load of those off-road tires is the 40%. At 5000 ft elevation, the air density is 17% less than sea level. I re-ran the range model using 5000' elevation at 70 mph and the range jumped up from 310 miles to 344 miles. About 10% improvement. Though every vehicle has a slightly different signature, as total road load power is a combination of tire rolling resistance and vehicle weight as well as and aerodynamic properties, elevation always make a difference. This explains why Kyle Connor now gets "amazing" range with every EV he range-tests. Ft. Collins is at 5000'.
Air density does impact the AC condenser cooling capacity too, but typically at high elevation we see lower peak ambient temperatures then near sea level, especially in the western US basin areas. 90 degrees in Colorado at 5000 feet provides a lot more ambient cooling capacity per cfm air flow than 110 in Las Vegas or Phoenix. AC cooling capacity more affects max charging speed than range. Pack and drive unit thermal systems typically are loafing during highway driving. Towing 10,000 trailer up the Hogback, though? Probably a different story

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