There are a number of features which can improve the safety of a car seat. All current car seats meet existing government safety requirements and pass standard crash tests. Some go beyond that.
The safest, perfect seat for every child and vehicle simply does not exist. On the other hand, there are some important features to consider on your next purchase. Car seats with few of these features can still be very safe choices, but they may require more time and effort to make sure they fit properly each time.
- 5-point harness. Experts agree and studies confirm that this type of harness is safest. The 5-point harness usually gives the best fit and reduces the chance of ejection. Some designs may easier to use than others.
- Wide, twist-free straps. Some harnesses have straps that twist easily. A twisted strap reduces the area that restrains a child in a crash, and this can result in burns or more severe injuries.
- Two-piece chest clips. These can also reduce strap twisting and are usually easier to use. They are often more difficult for a child to detach.
- Front harness adjustments. Some seats have a mechanism on the front of the car seat to adjust the tightness of the harness. Experts recommend that the harness be snug, such that you can't pinch any of the strap away from the shoulder. A tight harness can increase ride-down time, reduce the forward movement of the head in a crash and reduce the overall risk of injury. The easier the tightness is to adjust, the more likely it is that you will adjust it properly every time, no matter what clothing the child is wearing (though winter coats and other bulky clothing under the harness straps are not recommended). Some models even allow for the harness height to be adjusted from the front.
- Built-in locking clips. Some older vehicles will require the use of a metal locking clip to make sure the seatbelt holds the car seat properly and doesn't loosen over time. These clips are easily lost and often used incorrectly. A few models have built-in locking clips that are much easier to use and often result in a tighter fit.
- Seat belt routing path. In addition to built-in locking clips, some car seats have seatbelt routing paths which may make for better installations in some vehicles. Some seats also make it easier to actually route the belt from one side to the other with openings in the fabric cover for your hands. Vehicles with sloped rear seats or seatbelt buckles that come out from in front of the crease between the cushion and the back of the seat can make for difficult installations. Some car seats simply won't work with such seats. Finally, some seatbelt guides on certain belt-positioning boosters may be prone to misuse, causing excess slack in the seatbelt. In many cases, the only way to be sure is to try to install the seat in your own vehicle.
- Infant carriers with bases. Most infant carriers come with bases that can be installed separately. The base is left in the vehicle, and the carrier is easily installed or removed from the base without taking the baby out of the harness. An extra base can usually be purchased separately for another vehicle. Most carriers can be installed by themselves in a vehicle even without the base, but a few models may require the base for installation, so check to make sure.
- Size. Some seats may be too large to fit in vehicles with small rear seating areas, especially when rear-facing. For most car seats, this is not an issue, and may even be an advantage in a crash. Finally, it is sometimes necessary to choose a narrower model so that more car seats or passengers can fit side-by-side in the rear seat.
- Tether strap with easy adjustment. Top tethers may vary in their mechanisms for adjusting the length of the strap and ease for connecting/disconnecting the strap from the anchor. Some have easy-to-use push-button mechanisms, others use simple hooks.
- Rear-facing tethers and anti-rebound bars. These features are found on a few infant and convertible seats. Depending on the model, these features may improve crash performance, reduce the rebound of the rear-facing seat into the vehicle seat and increase the stability of the installation
- Foot Props. No current model in the USA uses a foot-prop to reduce any possible excessive downward rotation in a crash. This feature is common in other countries, like Australia. It may increase the safety of rear-facing restraints when used with heavier children.
- LATCH. LATCH is a newer system that allows a car seat to be installed without seatbelts. It can make it easier to get a proper fit in many vehicles. All car seats and most vehicles since 2002-2003 have this system. The car seat attachments vary significantly, some are easy to connect and release, others can be quite difficult.
- Head impact protection. Most car seats have an added layer of EPS foam or special plastic, similar to that used in bicycle helmets and protective gear. This is usually recessed into the plastic shell of the seat around the head and can improve crash safety in side impacts, rear impacts, and rebounds in frontal crashes. Some boosters may be made primarily of EPS grade foam. A few newer models tout special side-impact protection features as well.
- Increased weight limits. Rear-facing is safest for children since frontal crashes are more frequent and severe than other crashes. When rear-facing, the child is cradled by the whole seat. Front-facing, all the forces are transferred to the child by the harness straps, and the head is still free to be thrown forward. Most newer convertible seats have 35 or 40-pound rear-facing weight limits, and many infant carriers also go to 30 or 35 pounds. Much emphasis is also being placed on older children in boosters. Newer boosters have 80 or 100-pound limits, and there are harnessed front-facing car seats that go to 65 and even 90 pounds. Some restraints offer protection when only a lap belt is available.
- Adequate room for tall children. Some car seats have higher slots than others. When front-facing, a child's shoulders should be at or below the harness slots. Some car seats have higher backs than others. When front-facing, the tips of a child's ears should not be above the top of the car seat, to allow for whiplash protection. Some seats also have adjustable crotch strap positions for larger children. A proper fit is safer. Seats that accommodate taller children may allow you to use the car seat longer. A few older convertible car seats can ONLY use the top set of harness slots when front-facing, as the other slots may not be reinforced on these models.
- Reinforced carrying handles. While installed in a car, some infant carriers must have the handle in the "down" position. Left in the upright position, the handle can break during the rebound in a crash and injure the baby or other passengers. Other models may allow the handle to remain up at all times, and some may require the handle to remain up when installing in the vehicle; please check the manual.
- "Wings" for sleeping and protection. Some models have wide, padded wings on each side of the head. These are not only helpful to keep a child's head upright while sleeping, but they can also help to keep the child's head from hitting hard objects during a rebound in a side or rear impact.
- Recline. Some seats have built-in recline adjustments. This may help get the necessary 45-degree recline for newborns without the use of rolled-up towels or swim noodles in rear-facing operation. Older babies, toddlers, and preschoolers usually require less of a recline in a rear-facing car seat. Some models have handy recline indicators to help adjust them properly. While forward-facing, recline is not recommended unless allowed in the owner's manual.