passenger crashtests irrelevant for car seats??

I've been studying the crash test data and my logic leads me to say that the side impact passenger data isn't useful for carseats - am I right or nuts (or both). This is very counterintuitive as this is probably the one rating that parents care about most

In terms of NHTSA testing, the side impact test has both a front driver and rear passenger ratings. However many cars have a high driver but low rear passenger score (e.g., 2011 toyota camry). However this seems to primarily reflect the "restraint" abilities for a 5th percentile female (e.g., how well the seat belt protects a smaller person). However in the case of car seats, you have already pre-locked the seatbelts - so there is no risk of them not locking fast enough. Thus the side impact driver score and the structural data from IIHS seem more relevant. So if it has a high driver score, the low passenger is not important for children in car seats.

Does this seem right?

Not really. The scores reflect the interaction between the passenger, the seat belt, and the structural deformation of the side of the car. Even if the seat belt is pre-locked, devices like load limiters and pyrotechnic tightening sequences do factor in to the overall movement of the passenger. The amount of intrusion into the passenger space is also very important. Does this directly translate into how much protection a car gives to a car seat riding child...no...but better scores do indicate a better chance of not being injured in a side crash in general for all age groups.

Thanks for the response.

Agree w your point on load limiters. How important are they?

Also agree on the intrusion but that would seemingly also show up in the driver score and the IIHS side impact cage evaluation.

My car at least (2011 camry) doesn't have pre-tensioners on the rear outboard seats and the intrusion - am assuming that's what you meant by the 'pyrotechnics'.

I guess its just surprising to me that a lot of what the 5% female dummy is testing is not very analogous to a car seat - whereas at first glance rear passenger is what many people look at for their children in car-seats.

There are major structural differences surrounding the driver's seat that play into that driver's side score that do not play into the back seat. The framework for the driver's space includes the steering column and wheel, brake, gas, clutch linkages, dash instrumentation and framework for those (you don't want your speedometer becoming a projectile, and other things that change the whole equation. Back seat passengers do not have this rigid structure (which may be helpful or harmful) around their seating position. They are in the middle of the system, and thus at a weaker point (think breaking a stick. Easier in the middle, right?) of the car. The driver's seat has the potential to be forced into the back seat survivability space, the cargo in the trunk also. The B and C side pillars lack the structural reinforcement of perpendicular glass to shore them up.

The ratings are set up like this-I'm making the categories up because I'm too lazy to go look at what they actually are but you'll get the idea.

OK, so say they take a car and crash test it for side impacts. They then look at how much the door crushes in, how much the pillars surrounding the door push in, measure the amount of space the dummy has lost during the crash, take feedback from dummy sensors regarding head contact and neck flex, ride down time, how soon the belts locked and how much the belts loaded the dummy.

Then they assign a numerical value to each of those categories, do a bunch of high level math and extrapolate a number which corresponds to the very simplified scale that the consumer sees.

Yes, pre-tensioners are one of the pyrotechnic devices that I was talking about, but also, it applies to airbags.

IIHS side impact cage evaluation is an important tool for evaluating side impact safety, but it really only gauges the structural integrity of the outside of the car. The stuff inside, like do the seats collapse or tear free, is just as important.

You ask good questions.

Thanks so much for the information, very helpful. So I'll ask a few more questions that I have been struggling to understand

1)is the scoring on the IIHS side impact test easier than the NHTSA? I ask bc it seems many cars get all green in the IIHS test but then get a 2 on the govt side impact. Realize they hit at different heights but the difference seems extreme so I wondered if the govt test just has higher standards. (this seems true in general also as there are much fewer 5 star cars than IIHS safety picks)

2)what is the evidence on the benefit of rear side torso airbags for children in car seats? realize they are safe now, just have never seen statistics on how valuable they are. We are choosing between a car that has them vs not.

3)Is it worth trading off any increased injury in the crash tests to have a stronger cage? I've noticed that BMW, Mercedes and Audi all have much stronger cages than even the 5 star rated 2012 camry but in fact they all do slightly worse in the crash tests. On some blogs, people said that's because they are designing for more severe accidents. Is this true or are you always safer in the car that does better in the std crash tests?

4)Lastly is there a way to figure out the tradeoff between weight and crash scores - e.g., meaning how much safer is a 5 star rated 4500 lb car vs a 5 star 3500 lb car? or is a 4 star 4500 lb car better than a 5 star 3500 car? have been to the informedforlife website but he doesn't actually explain how he calculates this relationship.

Thanks so much!!!