Habits die hard. There has long as the heat engine is no longer necessary.
It is not uncommon to hear the engine roar in the morning in the parking lot. Why ? we could understand that 20, 30, 40 years ago the engine needed to “turn” or heat a little to allow better combustion and better lubrication, but for 10 years, at least, the engines are optimized for optimum efficiency at the first turn of the key. So make it a habit to start quickly and leave immediately. 1st 5 miles of your trip are always the most energy. So the less you wait, the more you save.
And even if it is hot outside and you want to refresh the cabin before leaving, the best way as the most effective and most economical is to lower the windows and start driving to enter the air. Then you can put the air conditioning, moderately.
Good road and see you tomorrow.