This is from consumer reports:
With all four models, problems occurred only when the seats were in their rear-facing position and attached with Lower Anchors and Tethers for Children, or LATCH, a universal connection system for child car seats and passenger vehicles in which connectors on the car seat attach to metal anchors in the car.
By contrast, when we connected the child car seats with car safety belts, all performed fine. So if you already own one of those car seats, you don’t need to throw it out. Just install it with the car’s own safety belt, not with the LATCH connection. Other details of our tests include the following:
• There appear to be problems in the way some car seats or their LATCH straps are designed. On multiple units, the LATCH strap broke on the Combi Avatar and the seat disconnected from the base on the Evenflo PortAbout 5. We noted a similar though less severe problem with the PortAbout 5 when we tested that model two years ago.
• A number of seats in the rear-facing position did a poor to fair job restraining the head of our test dummy from rebounding into the vehicle’s back seat after a crash.
What you can do
• Always use a car seat. All states require car seats for children under 4 years old; many require booster seats for older children. Consumers Union believes older children up to 57 inches should ride in booster seats.
• When possible, position the car seat in the center of the back seat, the safest place in a vehicle, even if that means attaching the car seat with the car safety belt and not the LATCH system.
• Never install a car seat using both the LATCH strap and the vehicle safety belt. This restricts the belts from absorbing crash energy.