MaxLTV

It very much depends on what car seat you put in. Some seats don't fit all the way into the seat and hang 1-3" away from the rear seat back at the bottom. That destroys a lot of space and makes the rear almost unusable. With seats that fit all the way in and have a relatively flat bottom, there is plenty of room for anyone under 4', maybe even 4'6". My 7yo is perfectly comfortable with Harmony booster, but complained with a Diono seat which allowed for probably 2" less legroom (and Diono also stretched out leather with its sharp edges on the back, so it had to go).

usrodeo4

On the rare occasion that my college aged son, wife and myself all go in the P car my wife can fit in the back without too many complaints and she is 5'7" ~ 125 lbs.