I know someone who had an attached tent for their...I think CR-V...or maybe Pilot (they got rid of the car years ago). The cool thing about it was that it allowed you the storage space in the truck of your car that you could access from inside the tent in addition to being able to turn on the car and heat/cool the tent with the AC/Heat. His was odd shaped where it attached to the car so that the exhaust wasn't inside the tent and just to be super safe, he used a dryer vent tube that he put over the exhaust to draw it away from the tent.
He said the heat would warm up the tent in no time, but last I knew, he had never needed to try it with the A/C.