Hmm, that shouldn’t be the case for ICE cars. ICEs are so inefficient at converting chemical energy into motion that they produce vast amounts of waste heat, more heat than would ever be required to heat the passenger compartment. “Turning on” the heater simply diverts some of the waste heat away from the external radiator.
Every car I have ever owned lost 20% mpg or more on hot and cold days when the AC or heater were working hard.
Hmm, that shouldn’t be the case for ICE cars. ICEs are so inefficient at converting chemical energy into motion that they produce vast amounts of waste heat, more heat than would ever be required to heat the passenger compartment. “Turning on” the heater simply diverts some of the waste heat away from the external radiator.
Outside air being colder would impact ratios plus winter gas.
AC will make a difference, but only a few percent; heater makes no difference.