"Which child car seat is safest?" There actually is an answer to this question. However, there is a 90% chance that you are not using the safest seat available for your child.
Certain child restraint manufacturers claim to have the absolute safest car seats on the market. These claims are completely unproven. Not necessarily untrue, but there is no metric or rating released to the public by the government. We know that all seats sold in the United States pass the same strict crash tests and safety requirements. Beyond that, you're taking the marketing department's word for it about the relative safety of their products.
Manufacturers can and do crash test their own products, but not in any standardized way, so it is impossible to compare the results. There are no official government safety ratings for child restraints, and any claims that a seat is the “highest rated for safety” should be taken with a grain of salt.
Here's the good news. Well, kind of. The design, features, brand, or model of a seat may make some difference in safety, but proper use of the seat is FAR more important. By some estimates, 90% of child restraints in the United States are installed or used incorrectly. Even IF there were a car seat that had been proven by crash tests to be the safest in the world (which, again, there is not), it may not protect your child if you have installed it improperly or buckled them in wrong. It also needs to be the correct type of seat for your child’s age, height, and weight. Obviously, it must fit appropriately in your vehicle as well.
The best way to make certain that you know how to install and use your child’s seat properly is to meet with a certified Child Passenger Safety Technician (CPST). Their job is to help you learn how to do it yourself—not just install the seat for you. It is widely believed that all police and firefighters are trained in car seat safety, but this is not the case. Rather than just stopping by your local fire station, visit safekids.org to search for a CPST in your area. Some of the technicians listed may be located at police and fire stations, but all of those listed are trained in child passenger safety. If you are referred to a CPST whose name is not found using the search tool on safekids.org, always ask to see their certification card so that you can verify that their training is up to date.
The bottom line: rather than stressing because you don't have the money for the so-called "safest car seat ever made," focus on proper use. The absolute safest seat you can buy is one that is properly fitted to your child and vehicle, and that you will be able to install and use correctly. Every. Single. Time.
For tips, advice, and the latest news on car seat safety, check out the links below: