i have 2 kids aged 4 & 2.5 never had any problem with room. but one thing i can tell u its the safest car/suv ive ever owned.
i had a bad crash with the kids in the X5 almost killed the other driver who i t-boned (100% other drivers to blame thank god i had a witness) we had $30,000+ damage to the X5 the other car was a total loss cause there wasnt to much left of it.
my kids, wife and i all walked away with out a scrach (air bags work good).