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Out of the multi-group child car seats we've tested, four scored highly enough to become Which? Best Buys, but we've also uncovered seven Don't Buys that you need to avoid.
Child car seats that you buy based on weight are known as 'group' seats. A multi-group child car seat spans more than one group, so it should last your child longer than a single-group seat. Find out more about
Some parents may find them appealing, as it means only having to choose and pay for one child car seat, which could last from birth or 12 months up to 12 years of age.
You might see multi-group seats called combination seats, and some retailers list them as Group 1/2/3 seats.
This means you have the option keep your child rearward-facing until they are four years old.
In the past, our testing has revealed that seats that try to do too much end up compromising on something.
Our car seat experts think you're probably better off buying a dedicated baby car seat, then a toddler seat and then a Group 2/3 child car seat, rather than choosing a multi-group, or combination, seat.
Children change too much for one seat shell to adequately provide the protection they need at each stage.
We've tested some good multi-group seats, though. These are the combination seats that have set themselves apart from the rest, and performed well enough to be Best Buys.
Some multi-group seats we've tested don't score highly for a number of reasons, including failing to position the adult seatbelt correctly on the child, or being difficult to convert between the groups, or failing to sufficiently protect the passenger when used in a particular group or mode.
A good car seat should be able to protect your child well enough in both front and side crashes, as you can't tell what type of accident you may be involved in. And as we expect parents to use a child car seat in all the modes and groups it's designed to cover, we limit the score to the worst-case scenario.
Some multi-group child car seats can convert into a backless booster seat in Group 3 mode.
Essentially, this removes the protective sides used in Group 2 mode, and simply helps to raise a child's body to a height suitable for using the adult seatbelt. Some have ‘horns’, which can help to guide the car’s adult seatbelt across your child’s tummy area.
Booster seats are temptingly cheap – some start from as little as £6 – and there’s no doubt they’re convenient. But while using any seat is better than using none, booster seats offer very little protection in a crash, particularly if you're hit from the side.
We've been testing child car seats for more than 50 years. Each car seat we review has been crash-tested in two different scenarios: a front crash, equivalent to a head-on collision at around 40mph, and a side crash equivalent to a car crashing into another car at around 30mph. We repeat these tests again and again, with the seat in all the different formats it can be used in.
We can go through as many as 15 samples of the same seat to get the final crash-test result.
Our experts have specially designed the crash tests, making them more demanding than the legal minimum standard requires. They’re derived from Euro NCAP, an organisation which carries out crash-testing on cars to show how well they protect occupants in severe accidents. We perform similar tests for car seats, and feel this more accurately reflects what could happen in a real crash.
These are wired up to record the crash forces on the most vulnerable parts of the body, and accurately indicate the risk of injury a real child could have in a crash.
If a car seat can be used in a number of different ways and attached by different methods (Isofix or the car’s seatbelt), we crash-test it in each format.