WattsUp, another engineer friend of mine once did thermal cooling analysis on Prius power electronics. You'd be surprised as to what he had to say about the lowered cooling performance of heat exchangers going up mountains at continuous max power at reduced air density (less mass flow). I2R heating. Hot day, high elevation (thin air) testing is important too. True, no air-fuel and emissions calibrations though. Also, quick elevation changes on seals is kind of a thing.
I've seen Hyundai, Honda, Chevy, Fiat, Ford, Toyota not-for-sale-yet cars up in the mountains over the last few years. You could test all the heat exchange performance you want on a dyno, with a wind tunnel, with low baro pressure in a chamber, to do the same thing. Most car makers have found its easier just to run them up a mountain a few times.
Back to the thread's actual subject: Elon Musk is 6'2'' (74") tall, and here he is walking in front of Model 3 prototype for scale (perspective is tricky though):
Looks like the car is wide. Our Focus Electric is 72" wide, and this one looks similar.