7 seater owner here, delivered the end of March 2021. 31,500 miles in 14 months, many 3500 mile round trips with 2 adults, 3 children and a 65 lb dog. The shade for the hatchback rear glass from Tesla makes a difference in the heat and direct sun's rays hitting the kid occupying the third row. There are no third row vents. The second row vents are in the middle console facing the second row seats. We have the middle row center seatback down flat which helps somewhat with the cooler air from the second row travel to the third row and the dog also likes it that way to go back and forth. There are two return vents that suck air out of the cabin, one under each front seat. There are no vents under the middle row seats. Adding a glass roof shade may make a further difference, I have not. Multiple brands are available now, seriously considering it. Blast the middle row vent at 8 or 9 if you have a kid in the third row and put the middle row center seatback down flat. Park in a shade if possible. Hope this helps.