Positioning Child Seats in Cars
If the middle rear seat has a three-point (lap and diagonal) seat belt, this is the safest place to put a child restraint (unless the manufacturer's instructions say it fits better in one of the other seats) because it is the furthest away from the sides of the car.
If the middle rear seat has a lap-only belt, check the child restraint instructions to see if it can be fitted with a lap-only belt. If not, fit the restraint on either side of the rear seat using the lap and diagonal seat belt.