My understanding is that it is for the cabin. BTW, for the cabin I did two things: - I installed a permanent shade for the sun roof. The sun roof is the stupi

My understanding is that it is for the cabin. BTW, for the cabin I did two things: - I installed a permanent shade for the sun roof. The sun roof is the stupidest thing ever, I hate it. - In the summer, I usually put one of those shiny umbrellas to the front windshield when parked. These two things alone reduce the cabin heat to an okay level.