well now, I was going to say late teens, but when it came to the front seat, it was the first one to yell shot gun, so the other two would yell shot gun for the ride back. mine just did not fight to much :D they just had there own rules on how things went, and they stuck with them. they all new the car did not go any where as long as there was bickering. I started that when they were very young. any time they would fight, I would pull over. so they learned very young not to fight in the car. God bless. Penny