Keys Disease

Keys Disease
Battling Keys Disease at the Futura Yacht Club in Islamorada, Fla. three years ago.

Monday, November 15, 2010

Deciphering Crash Test Scores: Seeing Stars

If you've shopped for a new car lately, you may have noticed on the window price sticker a box called "Government Safety Ratings." It's filled with stars next to descriptions of different sorts of crashes.

You may have thought, what do these stars mean and how do I use them?

Here's a rule of thumb for car shopping when safety is the primary concern: Bigger is usually better.

Yes, that's right. Both of our safety sources agreed that all the crash test scores in the world don't trump the basic truth about walking away from a crash: The larger the vehicle, the better chance you have.

In a crash, size does matter. All other things being equal, safety is basically a product of size and weight. This is particularly true in frontal crashes that account for half of crash fatalities.

Of course with SUVs, there are rollover issues; however, in accidents between two vehicles or a vehicle and an inanimate object, big wins the day.

A full-size sedan provides more protection in a crash than a subcompact, and a full-size SUV provides more protection than a full-size sedan, and so forth.

The question then becomes, which models within the different size classes are the safest? This is where test scores take on real meaning.

The National Highway Traffic Safety Administration (NHTSA) through its New Car Assessment Program, or NCAP, performs a series of crash tests and, based on the results, awards from one to five stars with five stars being best.

Here's our second rule of thumb: If safety is the primary consideration when buying a new vehicle, never settle for less than five stars for frontal crashes or four stars for side-impact crashes.

According to the Insurance Institute for Highway Safety (IIHS) and based on 2007 statistics (the latest available), 78 percent of all fatalities are a result of either a frontal or side-impact crash.

Why do we recommend five stars for a frontal crash and only four stars for a side-impact crash? Although NHTSA uses its system of stars throughout its tests, they translate into different information from test to test.

The compete list of stars and their meanings can be found in the FAQ section of http://www.safercar.gov/. This is also where you can find the scores for all the vehicles NCAP has tested.

In frontal crashes:

***** = 10 percent or less chance of serious injury.
**** = 11 percent to 20 percent chance of serious injury.

In side-impact crashes:

***** = 5 percent or less chance of injury.
**** = 6 percent to 10 percent chance of injury.

We believe that when safety is the primary criteria when purchasing a new vehicle, the chance for serious injury in a crash shouldn't exceed 10 percent.

The IIHS attributes 17 percent of all crash fatalities to rollovers.

NHTSA's five-star system takes on yet another meaning when applied to rollover crashes.

With regard to rollover crashes the stars don't correlate to the potential for injury, but to the potential for rolling over.

Here again we believe that only vehicles receiving the five-star rating should be considered when safety is the primary criteria.
According to NHTSA, all vehicles have about a 10 percent chance of rolling over in a crash. In rollover testing the scores for rollover potential are:

***** = 10 percent.
**** = 11 percent to 20 percent.
*** = 21 percent to 30 percent.
** = 31 percent to 40 percent.
* = 41 percent to 50 percent.

To put a finer point on rollover scores, the rollover rating may also include a bar graph with a diamond in it that provides a more precise rollover score between increments for comparison shopping.

If safety is your primary concern in purchasing a new vehicle, your research isn't finished.

The IIHS also performs a number of crash tests and awards safety designations of Good, Acceptable, Marginal and Poor based on a vehicle's crashworthiness.

When safety is the key criteria for purchasing a new vehicle, only those testing as Good should be considered.

On the surface the tests these two organizations perform appear to duplicate one another, but this is not the case.

Russ Rader, spokesman for the IIHS explained, "The tests are really complimentary because by-in-large, they are measuring different crash scenarios."

For example, the NHTSA frontal test is a full-width event crashing a vehicle head on into a stationary barrier, spreading the force of impact across the entire width of the vehicle.

The IIHS version also uses a stationary barrier, but the crash is offset, so that only part of the front end absorbs all of the force.

In side-impact tests, the NHTSA uses a battering ram barrier about the height of a passenger car bumper; the IIHS places the battering ram at about the bumper height of a full-size pickup or SUV.

The IIHS rollover scores provide methodology for rating a vehicle's crash worthiness in a rollover as opposed to NHTSA rating rollover probability.

The IIHS also performs an additional crash test rating head protection and whiplash injury in rear-end collisions.

Making it easy for consumers to find its highest-rated vehicles, the IIHS publishes its Top Safety Picks 2009 on its Web site at http://www.iihs.org/. It is comprised of vehicles scoring a Good in all categories, and also featuring electronic stability control.

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