I have gotten 420-440 miles per tank with my gas powered Gladiator. Of course, that was during summer months with the summer blend gasoline. I'm only getting around 360 miles per tank.
If the Jeep thinks the cabin is at or above 68 degrees when set to 68 degrees is will try to maintain that temp, so the air being discharged will be warmer. If it is reading above 68 it will blow cold to cool to the set temp.
2021 Willys here, I tend to drive the speed limit +/-5 mph. Mixed driving, lots of elevation changes and 50 miles each way for work. Been pleasantly surprised with my mileage to this point.
You obviously don't have to worry about salt use on the roads during winter. I can go through my washer fluid in a week during winter time as the salt spray from other cars coats the windshield and obscures vision almost completely.