True, but bringing the car from 0 up to 70 or from 100 down to 70 would take a tremendous amount of energy. If you program the car to start the heater or A/C while it is still plugged in, all of that energy saved is available for use. Of course, the range will still be reduced, but not as much.
Heating a gas car is essentially free. Cooling a small car takes about 4 hp off you engine’s rating.