Your EV Uses Energy to Keep the Cabin Comfortable
When sunlight passes through your vehicle’s glass, solar energy can heat the seats, dashboard, touchscreen, trim and other interior surfaces.
Your climate-control system then has to remove that accumulated heat to bring the cabin back to your desired temperature.
Tesla specifically notes that its Cabin Overheat Protection can operate the air conditioning when cabin temperatures rise and that running the climate system while unplugged consumes battery energy.