The ISOFIX system secures the child seat using compatible connection points on the car and the child’s car seat, removing the risk of a poor fit when using the car’s seat belt to secure the seat. Most cars now fit ISOFIX points in the rear as standard; some also provide them in the front passenger seat. If you are unsure whether or not your car has the correct ISOFIX system for your child seat, refer to the vehicle manual.
In Group 0+ and Group 1 seats, in particular, using the seat belt involves running the seat belt along a specific path through and across the seat frame, and often leaves room for error, such as the wrong route, too much slack or a twisted belt.
The ISOFIX system appears very effective: a study by the German Insurance Institute showed that 95% of child seats using ISOFIX were fitted correctly, as opposed to 30% for seats attached using only the car’s seat belt. With the exception of two-seater cars, ISOFIX will be mandatory in all new models launched from November 2012, and in all vehicles manufactured after November 2014.
Some ISOFIX seats also feature indicators that confirm when the seat is correctly fitted – this is particularly useful with Group 0+ baby seats that are frequently removed from the car and replaced, but since it is theoretically possible for the indicators to fail, it’s a good idea to always check the seat manually too.
What’s not to like?
One issue is expense – some car seats can cost almost twice as much when fitted with integral ISOFIX features. With some Group 0+ seats, you need to purchase an ISOFIX base (about £100) that is compatible with your model of seat; this attaches to the car’s ISOFIX points, and your child seat attaches to the base. The base also features a leg which rests against the floor of the car for added support.
Some child seats come with an integrated leg and connections points, but some also require a top-tether that attaches to points on the back of the rear seat. That means ISOFIX seats aren’t necessarily quicker to fit (a consideration if you frequently swap your seat between cars) but they make a consistently safe fit much easier to achieve than with a seat belt.
However, the biggest problem with the ISOFIX system is that, while the system was intended to be universal, not all ISOFIX seats and seat bases fit all cars with ISOFIX points. That’s because both can vary in shape, so they don’t fit together properly, even though they share ISOFIX connections. This means that before you start shopping for a child seat, you’ll need to check with your car or child seat manufacturer which products are compatible.