Hoping to help put a dent in the 10,000-plus deaths that occur each year as the result of rollover incidents, the Insurance Institute for Highway Safety has added one more element to its comprehensive testing regimen. Its new roof strength rating system evaluates a vehicle's ability to resist crushing forces that are incurred in this kind of potentially lethal crash. To determine the likelihood of a vehicle protecting passengers in case of a flip, this strength-to-weight index test uses a metal plate that exerts pressure against one side of a roof at a constant speed. To earn a "Good" rating, the roof must withstand a force of four times the vehicle's weight before it undergoes five inches of crush compression. A 3.25 mark merits an "Acceptable" mark, 2.5 is considered "Marginal" and anything below nets a "Poor."
In commenting on these rating values, the organization's president, Adrian Lund, noted that "Our research shows that a strength-to-weight ratio of 4 reflects an estimated 50 percent reduction in risk of serious and fatal injury in single-vehicle rollover crashes compared with the current federal standard of 1.5. We anticipate that our roof strength test will drive improved rollover crash protection the same way that our frontal offset and side impact consumer test programs have led to better protection in these kinds of crashes."
The first batch of vehicles to be subjected to this new IIHS torture test were a dozen popular compact SUVs, logical choices as the death rate from rollovers in all sizes of these versatile workhorses is 59 percent compared to a 25 percent mortality rate for cars and minivans. At the conclusion of this automotive squash match, the Honda Element, Jeep Patriot, Subaru Forester and Volkswagen Tiguan got the "Goods" while the Chevrolet Equinox, Mitsubishi Outlander, Nissan Rogue, Suzuki Grand Vitara and Toyota RAV4 rolled off with "Acceptable" ratings, the Honda CR-V and Ford Escape netted "Marginal" marks and the roof on the Kia Sportage was deemed "Poor."
Starting in 2010, the IIHS says it will make a "Good" roof-strength rating mandatory for any vehicle to be considered for one of its Top Safety Pick awards. The next two vehicle groups to be dealt a crushing blow by the IIHS are minicars and mid-sizers.