New test results show that some automakers are doing a good job of designing vehicle roofs that perform much better than current U.S. federal rollover standards require. But the roofs on some other vehicles need improvement. In the first U.S. Insurance Institute for Highway Safety (IIHS) roof strength tests of so-called midsize SUVs, six earn the top rating of ‘good’ for rollover protection, one is ‘acceptable’ and five others earn the second lowest rating of ‘marginal.’
The “midsize” SUV models earning good ratings are the 2010 GMC Terrain, 2010 Jeep Cherokee, 2010 Toyota Highlander, 2010 Toyota Venza, 2011 Jeep Grand Cherokee and 2011 Kia Sorento. The 2010 Ford Edge is rated acceptable. The worst performers, which earn marginal ratings, are the 2010 Honda Accord Crosstour, 2010 Honda Pilot, 2010 Mazda CX-7, 2010 Mitsubishi Endeavor and 2010 Nissan Murano.
In addition to earning good ratings for rollover protection, the Equinox, Grand Cherokee, Highlander, Sorento, and Venza also earn the Institute’s TOP SAFETY PICK award. To achieve this, a vehicle has to earn good ratings for occupant protection in front, side, rear, and rollover crashes. It also has to have electronic stability control.
Vehicles rated good must have roofs that are more than twice as strong as the minimum required under the current U.S. federal safety standard. According to the IIHS, top performance in the roof test is important because nearly 10,000 people a year are killed in rollover crashes. Roofs that don’t collapse help keep people inside vehicles when they roll.
In the Institute’s roof strength test, a metal plate is pushed against 1 corner of a roof at a constant speed. To earn a good rating, a roof must withstand a force of 4 times the vehicle’s weight before reaching 5 inches of crush. For an acceptable rating, the minimum strength-to-weight ratio that’s required is 3.25. A marginal rating value is 2.5, and anything lower than that is poor.
Other SUVs will be tested later during the year.