Go here and click on ‘seating greater than 5’ or ‘3rd row’ seat. Smaller vehicles won’t have rear vents located on the roof. Another thing you might try is redirecting the center vents so that they blow towards the roof at the rear of the car, if you don’t already. That might help. I know that I put the side and center vents on me when I drive on a hot day, and maybe you do, too.