Maxi-Cosi Emerald S i-Size 360° Swivel, 40–150cm

The Maxi-Cosi Emerald S i-Size sits at number one in our ISOFIX car seat guide. It is a £239 rotating seat sold for 40–150 cm, described as birth to 12 years and Group 0+123, with ISOFIX connectors, four recline positions and 14 headrest height positions. It carries a 4.6 out of 5 rating from 666 ratings.

The awkward part is in the seat's own spec table. The listing gives a rear-facing maximum weight of 36 kilograms — exactly the same figure it gives as the maximum weight recommendation for the seat as a whole. Nothing in the six bullets explains what that rear-facing figure refers to, and no bullet states any rear-facing height, weight or age limit of its own; the only limits spelled out anywhere are the 40–150 cm span and the 36 kg. The same table lists a 5-point harness next to Group 0+123, without saying at what point a child moves from the seat's own harness to the car's belt. The rating breakdown is another set of numbers that does not close: the five bars add up to 100 against the 666 ratings reported at the top of the page. Everything here comes from the Amazon listing as it appears, not from a seat we have fitted or tested.