March 29, 2012 -- Female dummies are turning out to have some serious influence in Detroit.

For years the auto industry and federal safety agencies conducted crash tests with dummies modeled on males only. Now dummies modeled on females have joined their ranks; and data gleaned from them is beginning to ifluence everything from vehicle design to safety ratings to consumer purchasing decisions.

Jack Jensen, a General Motors Technical Fellow and group manager for GM's Anthropomorphic Test Device lab in Milford, Michigan, points to some 200 dummies, each costing as much as $200,000. "We have all different shapes and sizes," he says, "about 20 different types." They allow GM to simulate big and small men, big and small women, children of various ages, infants, even whole families.

About 35 of the 200 can be considered female. Their gender is defined by more than height and weight. Some have wider hips than would a male of comparable size. Some have chest-jackets simulating breasts.

The reason for using female dummies is simple, says Lynda Tran, spokesperson for the National Highway Traffic Safety Administration (NHTSA): Studies show that women, having smaller bones and lower bone density, are at greater risk than men of suffering injury or death in crashes. Their less muscular necks make them more vulnerable to whiplash. In general, smaller people cannot tolerate crash forces as well as can full-sized men.

Yet even though male dummy testing dates back to WWII or earlier, NHTSA didn't begin to make wide use of female dummies until 2003. GM didn't start before the late '80s. How come? Isn't the driver of car these days as apt to be a woman as a man?

"Manufacturers and designers used to all be men," explains Dr. David Lawrence, director of the Center for Injury Prevention Policy & Practice at San Diego State University, which publishes at Safetylit.org a weekly update of safety literature culled from some 9,000 scholarly journals around the world. "It didn't occur to them they should be designing for people unlike themselves. Well, we got over that."

The latest vehicle safety ratings by NHTSA take both men and women into account. Go to the Administration's consumer shopping tool at Safercar.gov, for example, and you can compare not just the relative crash-worthiness of 74 different vehicles, but you also can see--in a limited way--which ones provide better safety for women.

Click on the 2012 Nissan Versa , for example, and you'll see that in a frontal crash, the protection afforded a female passenger rates three stars out of a possible five (the more stars, the better the level of protection). That's an improvement from the car's corresponding 2011 rating (two stars) but not as good as the comparable rating for the 2012 BMW 528i (four stars).

Says Tran, "As a public health and safety agency, NHTSA is continually working to ensure all vehicle occupants are protected--regardless of age, gender or size." The agency's use of female dummies, she says, is "more extensive than anywhere in the world."

Be that as it may, any woman trying to use Safercar.gov to determine in which car she would be safest as the driver (as compared to passenger) is in for a frustrating experience: Two out of the three of the NHTSA's test situations presume the driver to be male: In the head-on crash and the crash into a side barrier, it's a male dummy behind the wheel. Data for a female driver is not provided. Only in the third test situation--a side crash into a pole--is the driver female.

Want to know which vehicle offers best protection, in that crash, to the female driver? You'll have to search each and every one of the 74 vehicle ratings: the site does not allow you to search by type of crash or to sort the results. Moreover, for this type of crash as for the other two, different vehicles may all have earned the same star-rating.

It's not that the government doesn't have a wealth of additional crash data applicable to women behind the wheel. But it comes from a different series of crashes designed to test whether a car meets--or doesn't meet--the minimum federal safety requirements. The test is binary: a car either passes or it doesn't. It's not like the 5-star rating," explains an auto safety expert. "There aren't any 'degrees' of safety." Cars that do not pass never make it to the consumer market.

But as unsatisfying as the data may be from a consumer standpoint, engineers already are using it improve cars' safety for women, whether drivers or passengers.

Says Russ Rader, spokesman for the Insurance Institute for Highway Safety, "One of the reasons we started using female dummies is the way women sit in a vehicle." They tend, for example, to position their seats farther forward, to compensate for their smaller stature. "So, if you imagine a side-impact crash, where an SUV or a pickup, say, is hitting the car, the position of the woman's head is right in the center of the [side] window, where an object is likely to be coming in. The man is sitting farther back. In a 4-door car, he's getting more protection from the pillar" (the post in between the front door and the back door).

To accurately model that difference, says Rader, the Insurance Institute used a female dummy for its 2003 side impact tests. "We used a female [dummy] because of the vulnerability of women to that kind of crash." The data led to improvements in the design of side air bags, positioning them so they offer better protection to a female passenger.

Beyond this, Rader doesn't expect female dummies to play much more of a role in future safety design. "We do our own tests, different from the government's," he says. "We don't see a significant difference between females and males. In the frontal crash testing we've done, for example, we don't find one."

Seat belts and air bags, he says, have evolved to the point where they now do a good job protecting a car occupants of all shapes and sizes.

"The key takeaway for consumers," he says, "is not that women should be concerned that safety tests don't represent them. It's that you ought to buy the most crash-worthy vehicle overall that you can find. That way, you'll be getting the highest level of protection that you can, no matter what your gender."