Communities I'm in have had a lot of talk about car seats lately, and it's concerning to me that so many people think that a convertible car seat meant to safely hold a 50-pound child will safely hold a 6-pound newborn as long as the baby looks secure, making an infant-specific seat a waste of money. LOOKING secure and BEING secure are two very different things.
Right now carseats in the US must only pass a straight (head-on) bench-seat test going 30MPH, and when the NHTSA did additional testing that doesn't count toward the pass/fail rating (side impacts), many more sears failed. But as side impact has no bearing on whether or not a seat passes, many seats pass that really shouldn't. Most crashes in this country are side impacts.
The U.S.'s safety requirement for car seats is one of the lowest in the world and simply received a pass/fail rating. That's all. There is a more stringent rating system in place for ease of use for car seats than there is for how likely a seat is to save a life in a crash. When the NHTSA did that additional testing, the government defined those failed tests as "research", which is why the 31 seats out of 66 used in that test that failed still have a pass rating.
A front-end crash will result in most seats protecting an infant's head, though the sled benches used can't take into account what happens when a baby seat hits the front seat because there IS no front seat. But a side impact is a drastically different type of accident. There is far more room in that convertible seat for an infant's head to snap sideways, and toweling and whatnot that a lot of parents thing looks more comfortable and is secure enough because it looks secure isn't going to absorb the impact.
It just makes no sense why, when so much can already go wrong in a crash, so many parents still insist on buying a seat that is too big and "making" it work with pads and towels. No one's going to buy a 2-year-old toddler shoes meant to be still be worn when he's 4 because that much extra room will make him likely to fall and hurt himself, yet so many parents don't think twice about buying a newborn a car seat meant to be used at 4 years old when life and death is involved.
With life and death matters, when only a pass or fail is given, when the testing methods used don't simulate a real life accident, why take a chance? "All seats have to pass a test" really means jack shit when the test is so lax and doesn't simulate real life.
Well, someone else's baby can be the one with the higher chance at death. Saving a couple hundred bucks isn't worth the increased chance of our own baby dying in an accident. We value our baby's life a good deal more than a couple hundred dollars.