2 Car Seat of the Car Is the Best
Positioning Child Car Seats in Cars
When choosing a child car seat, consider where you wish your child to sit in the car, and check that the child seat can be properly fitted in that position.
Position 1: Front Passenger Seat
It is safer for your children to travel in the rear seats than the front. Some parents like to be able to keep an eye on their baby or child and so put them in the front. But, they are safer in the rear, and remember, if you are trying to drive and look after a child at the same time, you will be distracted and more likely to crash.
If a baby or child needs to be monitored, for health reasons for example, ask another adult to ride with them in the rear.
NEVER put a rearward-facing baby seat in the front if there is an active passenger airbag. It is illegal and dangerous to do so, because if the airbag goes off, it will hit the baby seat and fling it forward with considerable force.
If the car does not have airbags in the front, or if they can be deactivated, or if the car has sensors which switches the airbag off automatically when you fit a child seat, then you can legally carry a rearward facing baby seat in the front. However, it is still better to fit it in the rear.
If you must fit a forward-facing seat in the front, make sure that the car seat is as far back as it will go so your child is as far away from the dashboard as possible. Double check that the child seat is very securely held by the seat belt and your child is securely held by the child seat's integral harness or the car seat belt (depending on the type of child car seat).
Position 2: Rear Seat Behind the Driver
If possible, use one of the other rear seats. If you use this seat, you may have to get the child in or out of the car on the road side of the vehicle. However, if you normally park with the driver's side next to the pavement, this seat would be better than the opposite side.
If you use this seat, make sure the child seat can be fitted in this position correctly.
Position 3: Middle Rear Seat
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 one of the other seats is better) 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. Most child car seats require a three-point seat belt. If this is the case, fit the seat on a rear seat that has a lap and diagonal seat belt.
If you are using an Isofix or i-size child seat you can only use the middle rear seat if it has Isofix points.
Position 4: Rear Seat Behind the Front Passenger
It is better to use this seat, than the one behind the driver, because it means you can normally get the child in and out of the car on the pavement side.
Make sure the child seat can be fitted in this position correctly.
2 Car Seat of the Car Is the Best
Source: https://www.childcarseats.org.uk/choosing-using/positioning-child-car-seats-in-cars/