My family tried out the 7-seater last week in the Tesla showroom at the Fashion Island Mall in Newport Beach. Before we arrived, I had low expectations that the third row seats would be comfortable and practical and that Tesla only had this option in the Model Y to convince you that the Model X would be a better fit.
I'm 5' 10" with a tall torso (shorter legs than average), and my partner sat in the middle row while I sat directly behind him in the third row. He adjusted his middle row seat to give me adequate leg room in the third row while still giving him adequate leg room in the second row. He is 6' 0" and also has a tall torso (33" pant leg inseam). He then switched to the front row seat and found more than adequate arm length and leg room there without adjusting its position. While in the third row, I had to tilt my head about 30 degrees to have the top of my head avoid touching the glass of the rear hatch.
In sum, I was pleasantly surprised at how I could fit in the third row for a short trip with other tall persons in the seats directly in front of me in the other two rows and expect that somebody with about a 2" shorter torso (my pant inseam is about 32.5") would be fine in the third row for long trips.
