I agree about 59 F but I've shifted my temperature range up to avoid using the heater. My BMW i3-REx uses electric heaters and that eats into the range.
I probably should mention turning off or minimizing all optional loads:
- A/C or heater OFF - heavy electrical load
- brights OFF - the LED low beams when testing at night IF safe
I didn't mention calculating the 'density altitude' so you correct for temperature and altitude changes. But I don't look forward to explaining how it works.
Bob Wilson