IIHS chooses 9 more Top Safety Picks

Nine more vehicles have earned Top Safety Pick awards from the Insurance Institute for Highway Safety (IIHS) following a new round of roof-crush tests.

The Audi A4 and Q5, Ford Flex and Fusion, Hyundai Tucson, Lincoln MKT, and Volkswagen Jetta Sportwagen all earned the Institute's highest safety rating.

To earn a Top Safety Pick rating, a vehicle has to earn Good ratings in the Institute's 40- mph frontal offset crash test, the 35-mph SUV side-impact test, a rear head restraint configuration analysis, and IIHS's new roof-strength test. IIHS rates vehicles in all four tests on a scale of Good, Acceptable, Marginal, and Poor.

To earn a Good rating in the new roof-strength test, a vehicle has to have a strength-to-weight ratio (SWR) of 4:1 or better. That means the roof would support an impact with four times the force of that vehicle's weight without deforming more than five inches. An Acceptable rating requires a roof-strength ratio of 3.25. Below a ratio of 2.5, earns a Poor rating.

The cars tested achieved the following SWR ratings:

• Audi A4: 4.6
• Q5: 4.41
• Ford Flex: 4.51
• Fusion: 4.78
• Tucson: 4.43
• Lincoln MKT: 4.29
• VW Jetta Sportwagen: 5.13

The rating for the Ford Fusion also applies to its twins, the Mercury Milan and the Lincoln MKZ.

Ford recently modified and strengthened the roof structure of the Flex, Fusion, and MKT, so these ratings apply only to Flex models built after January 2010, MKTs built after March 2010 and Fusions built after April 2010.