NHTSA vs. IIHS? Which would you go by?

[bearwithmoi]

I've been car shopping a while and are all over the board as to what we're looking at. We're taking all the safety ratings into account. NHTSA just posted their 2008 Honda Accord ratings with 3 stars for rear seat side crash safety. But IIHS listed the 2008 Accord as one of their top safety picks, with "good" ratings for all side impact tests (although structure/safety cage is "acceptable).

Why would there be such a difference - especially if the IIHS test happens at a faster speed? What am I missing?

My concern is that I can't rely on any of these ratings.

Any thoughts?

Thanks,

Sarah

[twokidstwodogs]

They are quite different crash tests, which is why you get such different ratings. Ideally, you want a car that does well on all of them. (Three stars on the NHTSA side impact test is pretty low. Does the 08 Accord have side curtain airbags for rear passengers?)

Have you been to www.informedforlife.org yet? The person who runs that site puts all this data into an algorithm that takes into account all this data. It enables you to draw useful comparisons between cars. One drawback is that when there's no information available on a particular car, he will use the average for a car in that class. So some cars end up looking less safe than they actually are. But any car near the top of that list is extremely safe.

[bearwithmoi]

Thanks for the Informedforlife suggestion. I checked and their ranking for the 2008 Accord does not have the NHTSA side impact ratings so I e-mailed them to suggest that they run it again because it is such a big discrepency.

[southpawboston]

plus, IIHS does not use rear seat test dummies in their evaluation. only front. NHTSA takes load measurements on both the front seat and rear seat dummies. that's why it got three stars for the rear passenger. surprising, actually, considering that it's an accord and it has side curtain airbags.

[CPSDarren]

I've been car shopping a while and are all over the board as to what we're looking at. We're taking all the safety ratings into account. NHTSA just posted their 2008 Honda Accord ratings with 3 stars for rear seat side crash safety. But IIHS listed the 2008 Accord as one of their top safety picks, with "good" ratings for all side impact tests (although structure/safety cage is "acceptable).

Why would there be such a difference - especially if the IIHS test happens at a faster speed? What am I missing?

My concern is that I can't rely on any of these ratings.

Any thoughts?

Thanks,

Sarah

The IIHS test uses a shorter female dummy and simulates a higher oncoming vehicle like an SUV. Most importantly, it also considers head injury measures, which are the emphasis of the test. This gives a big advantage to models with side impact airbags with head protection features.

The NHSTA test uses a taller, average male dummy and an oncoming bumper simulating a typical car. It measures head injury criteria but does not include them into the star rating. It is primarily for chest/torso injury measures.

As said already, ideally you want a vehicle that does well in both tests and not focus on one or the other.

[twokidstwodogs]

Thanks for the Informedforlife suggestion. I checked and their ranking for the 2008 Accord does not have the NHTSA side impact ratings so I e-mailed them to suggest that they run it again because it is such a big discrepency.

There's also a tool on that site that allows you to run the algorithm yourself with more information. But I suspect the site owner will get back to you soon. I've emailed him before and gotten a very prompt answer.

[bearwithmoi]

You guys are good! I e-mailed the person who runs the informedforlife site and he got back to me immediately! He has already updated the site to reflect the ratings. He said that 3-star ratings are very rare, and although it's only for the rear impact of the backseat, it is still important if you are carrying children or other passengers in back.

[southpawboston]

He said that 3-star ratings are very rare, and although it's only for the rear impact of the backseat, it is still important if you are carrying children or other passengers in back.

um... i thought that the rear impact tests conducted by IIHS are for front passengers only, not rear. it is not an actual crash test. it is a sled test of a front seat to see how well the seat protects the front passenger from whiplash and other neck/back injuries following a rear impact. it is a test of two parts: a geometry evaluation (how well the headrest "fits" the head), and a dynamic test (the sled test) which evaluates how well the dummy is protected as the seat bends rearward.

it is completely irrelevant to how well a child in a carseat would fare in a rear impact. it doesn't apply at all. it also is completely independent of how well the rear of the car holds up structurally. it is a measure of how well the seat itself protects the front seat occupant.

read more about the IIHS rear impact test here (http://www.iihs.org/ratings/head_restraints/head_restraint_info.html).

[Jeanum]

I think Bearwithmoi is referring to the Accord's rear seat's side impact crash score, not any rear end impact ratings. :) The three star score she mentions is the NHTSA side impact rating for the Accord's rear seat.

[southpawboston]

oh. duh. i just read the last post and saw "rear impact of the backseat" and neglected to read the previous posts. :o too much eggnog. :whistle:

[Jeanum]

No problem, you're just trying to be helpful. Eggnog, ick. :p