Why You Need At Least 6 Airbags

For many years, car makers have participated in so-called "airbag wars". As consumers and crash testing have demanded more and more airbags, automakers have phased them in - often years ahead of legal requirements. While only two airbags - a driver and passenger front airbag - are legally required, it's hard to find a new vehicle with less than six. 2008 was the first year that a majority of new vehicles had six airbags, so vehicles with the six airbag system and good crash test ratings are now available for cheap. 

Let's look at front airbags first. Front airbags have been mandatory since the 1999 model year, and well over 90 percent of vehicles on the road are equipped with them. Some people still fear airbags or find them unnecessary, in part due to some injuries and deaths caused by some "first generation" (pre-1998) airbags. It is now nearly twenty years after the last "first generation" airbag was manufactured, and the number of people scared of airbags is diminishing. 

The lifesaving potential of front airbags is graphically demonstrated by this crash test of a 2005 Honda Odyssey into a wall at 35 mph. With its front airbags intact, the 2005 Odyssey received a perfect five-star result for both front occupants, meaning that a real person could walk away from a similar crash. Take away only the airbags, and the dummies' heads violently slam into the steering wheel and dashboard in the exact same crash scenario. Although the dummies were not instrumented in this test, the force of the impact means that a real person would probably have been killed or severely injured in the Odyssey with no airbags. 

Some may say that only a driver airbag is necessary, because the passenger has more room to slow down. The passenger airbag is necessary, as demonstrated by two NHTSA crash tests into a wall at 35 mph. The 2008 Infiniti EX35 was tested twice due to an airbag failure in the first test. In the first test, the passenger airbag did not inflate due to a fault with the occupant sensor. Infiniti corrected the fault and recalled the earlier vehicles, and the EX35 was re-tested. In the re-test, both airbags deployed properly.

Serious injury is deemed to be likely when the head-injury criterion (HIC) exceeds 1,000, Chest G's exceed 60, or loads on any femur exceed 2,250 pounds. In the two EX35 tests, the chest and femur force levels were all well below these values. The passenger's HIC was 1,329 in the test where the passenger airbag failed, indicating that severe head injury was likely. In the re-tested EX35, the passenger's HIC was 592, indicating that any head injuries would be minor. Because the driver airbag deployed properly in both tests, results were not significantly different; driver HIC was 533 in the first test and 548 in the second. 

Both the side torso and side curtain airbags are necessary. With just the curtains, your head is protected, but your chest - and its vital organs - are left unprotected. This is demonstrated by two IIHS side crash tests conducted on a 2009 and a 2012 Dodge Ram. The Ram had a solid structure, but without the side torso airbag, the driver dummy in the 2009 model's chest was unprotected, and a high risk of rib fractures and internal organ injuries knocked the overall score down to a Marginal. The 2012 model, equipped with both a side torso and side curtain airbag, scored a Good, with a much lower risk of serious injury to the driver. 

Without side curtain airbags, your head is very vulnerable to injury in a side impact, even if you still have the side torso airbag. Some vehicles, primarily in the early to mid 2000s, were equipped with "combination" head and torso side airbags that were mounted in the seat like a torso airbag but had an upper chamber to protect the head. These can offer decent protection to front occupants, but offer no protection against flying glass and debris and also give no protection to anyone in the back. A curtain airbag is far superior. 

The 2004 Toyota Camry and 2004 Honda Accord were both offered with optional side torso and side curtain airbags. In the IIHS side crash test, which simulates what happens if you are T-boned by an SUV at 31 mph, the driver dummies in both vehicles not equipped with side airbags recorded forces that indicate that a real driver probably would have died from massive head trauma. With the side torso and side curtain airbags, the dummies recorded forces that indicate that a real driver would probably walk away with minor injuries. 

With the dummies used in this test, a HIC of over 700 indicates that serious injury is likely. Without side airbags, the driver dummy in the Camry's HIC was 1,619 and the driver dummy in the Accord recorded a HIC of 2,548. Both of these values indicate that fatal head injury is likely. With the side torso and side curtain airbags, the HIC was 406 for the Camry and 488 for the Accord - painful, but likely to cause only minor injuries. 

There are other airbags in many cars today - knee airbags, seat cushion airbags, seat belt airbags, rear curtain airbags, even a front center airbag - but the basic set of six is the minimum. These extra airbags probably provide some extra benefit, so if the vehicle you want has more than six airbags (even a double-digit count), go for it! The largest number of airbags put in a production vehicle so far has been 12. There are many new cars with 10 airbags - driver front, passenger front, driver knee, passenger knee, driver side torso, passenger side torso, rear left side torso, rear right side torso, left side curtain, and right side curtain. With some of these vehicles under $20,000 new (and used variants under $10,000) you don't have to break the bank to get even 10 airbags. 

Once you have the basic set of six airbags, more airbags don't necessarily equal a safer vehicle. Remember to check crash test results and accident avoidance features.

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