I have two kids . . . one is 6'4" and the other is 6'2 and still growing. When he was 10 he went in a 911 and said is was the most uncomfortable car he has ever had the pleasure of being in the back of.
Take Ekona, he's going on a jolly round Europe for a week or so, just him (don't think the mrs is going) and he's taking the back seats out . . dont think thats to save weight