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The Insurance Institute for Highway Safety has put a new crop of large luxury vehicles through its crash test gauntlet, and the Cadillac CTS and Infiniti M joined some impressive company in scoring a Top Safety Pick designation. The CTS and M clinched the highly regarded award by receiving the top score of "Good" in roof strength testing. To achieve the top score in rollover safety, a vehicle's roof has to be able to support four times the weight of the entire vehicle.

The Top Safety Pick designation is handed out only to vehicles that received a "Good" score for all four IIHS crash tests while also featuring standard stability control to help avoid accidents altogether. The Cadillac and Infiniti join the BMW 5 Series, Lincoln MKS, Volvo S80, Hyundai Genesis and the Mercedes-Benz E-Class as Top Safety Pick winners.

Since large luxury vehicles cost so much and contain so many safety features, it's not all that surprising that so many models aced IIHS testing. But not all vehicles passed the test with flying colors. The Lexus GS and Audi A6 managed only an "Acceptable" score in roof testing, while the aging Acura RL lagged behind the competition with a "Marginal" rating. Hit the jump to read over the IIHS presser.

[Source: Insurance Institute for Highway Safety]
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New rollover test ratings: Two large luxury cars earn good ratings and Top Safety Pick award

The 2011 Cadillac CTS and Infiniti M37/M56 earn the top rating of good in recent roof strength tests that assess how well vehicles would protect people in rollover crashes. The Lexus GS and Audi A6, both tested as 2010 models, are rated acceptable, and the Acura RL, also a 2010, is rated marginal for rollover protection.

After the latest roof strength tests, the CTS and M37/M56 also earn the Institute's Top Safety Pick award with good ratings in all 4 Institute safety evaluations, and electronic stability control, which research shows can help drivers stay out of crashes altogether.

"The test results show that manufacturers are moving quickly to improve the rollover safety of their newest designs," says Institute president Adrian Lund.

The BMW 5 series, Hyundai Genesis, Lincoln MKS, Mercedes E class, and Volvo S80 also are Top Safety Pick winners in the large luxury class based on test results released earlier.

The Institute evaluates rollover protection using a roof strength test. In this test a metal plate is pushed against one corner of a vehicle's roof at a constant speed. The maximum force sustained by the roof before 5 inches of crush is compared to the vehicle's weight to find the strength-to-weight ratio. This is a good assessment of vehicle structural protection in rollover crashes. Good rated vehicles have roofs that can withstand a force equal to at least 4 times the vehicle's weight.

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    • 1 Second Ago
      • 4 Years Ago
      It sad to see how much Honda has fallen from where they used to be. At one time they had good, reliable, safe and fun to drive cars and now they have..... well I think it's easier to just leave it there.
      • 4 Years Ago
      LOL. Moron.
      • 4 Years Ago
      wasn't Acura running tv ads about every car in their line-up being the safest like no other manufacturer can claim... me = confused.
        • 4 Years Ago
        I've owned both an A6 and a CTS back to back and I'm not at all surprised the CTS did better. The roof pillars are ridiculously large on the CTS. To be honest, I'd rather they were thinner and the car did only as well as the A6 in these roof tests.

        These pillars are just too thick, they block your view. And I'm not even talking about the huge D pillars, those turn out to not matter at all, it's the thick A and B pillars that I don't like.
        • 4 Years Ago
        don't matter who does the test
        for you to claim you must meet all of them

        and they are in last place, so it's not like they fell midpack, but then that is the oldest architecture of the cars tested followed by the Lexus and Audi, so the test reveals what is expected. the new comers are on top and Maybe Volvo is the exception
        • 4 Years Ago
        I second that. WTF Acura?
        • 4 Years Ago
        Yeah I was gonna say that too, I remember them claiming all of their cars had a 5 star rating. Not anymore I guess..
        • 4 Years Ago
        That's NHTSA, this is IIHS. Two different organizations running different tests.
        • 4 Years Ago
        I'm not suprized at all about Acura's weak ratings... a lot of thier cars don't even pass minimum requirments in germany. I am very suprized about the A6.... that car is built like a tank... with saftey being one of Audi's top priorities, they are going to flip out over this...
        • 4 Years Ago
        I would have thought the Ford Taurus, being a family-oriented sedan would make it as a top safety pick... Am I right or am I wrong?
      • 4 Years Ago
      I haven't touched physics in about 10 years, so I'm hoping somebody else can tell me my math is wrong.

      A roof structure that can withstand 4x the weight of the vehicle implies that the vehicle can impact, roof side down, at 4x gravity (39.24 m/s^2, or 4 seconds of falling)? If so, does that mean that the instantaneous impact speed of the roof against the ground would be ~87.7 mph?

      If that's the case, does that suggest that a vehicle of equal mass can drive into the top of your car at highway speeds (assuming your car was lying on its side) without the roof collapsing (assuming your car was fixed and wouldn't slide).
        • 4 Years Ago

        > If so, does that mean that the instantaneous impact speed
        > of the roof against the ground would be ~87.7 mph?

        Sadly, no.

        Let's give it a try with some seriously simplistic assumptions. For the Benz. In SI units.

        Assumption 1: roof crush is some 30 cm = 0,3m
        Assumption 2: acting force is constant during the time of the crush
        Assumption 3: the vehicle landing on its roof decelerates in a constant manner
        Assumption 4: The vehicle weights some 1700 kg.

        The force acting is 20k pounds ~= 90.000 Newtons.

        Impulse eqation says us the force F acting in given time t equals the mass m and the change of velocity dv.

        F * t = m * dv

        Equations of uniformly accelerated linear motion tell us that the distance s equals the sum of start velocity vS plus final velocity vF, multiplied by the time t of the acceleration, divided by 2.

        s = (vF + vS) * t / 2

        Final velocity, however, equals 0. The vS then equals dv. Replacing the variables with values we know, we have:

        90.000 * t = 1700 * dv

        0,3 = dv * t / 2

        t ~= 0,1 [seconds]
        dv ~= 6 [m/s] ~= 21,6 [km/h] ~= 13,4 [mph]

        There we are. The Mercedes Benz tested would withstand the fall onto its roof when hitting the ground traveling downwards at 21,6 [km/h] ~= 13,4 [mph]. Its competitors respectively less.

        Hopefully, I didn't make any stupid mistakes.
        • 4 Years Ago
        Assuming force is evenly distributed, of course.

        What I'm getting at is... if the car were fixed in place on its side, could a 3500 lbs car @ 90 mph or a 10,000 lbs truck @ 30 mph hit the roof of the Benz without it caving? That just seems too incredible to me (which is why I think my numbers are wrong).

        (again, assuming the impact were evenly distributed over the roof of the vehicle)
        • 4 Years Ago
        No, since you have to take into account how much of the roof is taking that impact, and the testing here is likely to spread more of the weight over the whole roof, whereas a car ramming into your roof at 90mph would likely be concentrating the force on the area of initial impact.
        So uhh don't go getting hit by cars doing 90.
        • 4 Years Ago
        IIRC, a big metal plate is pushed against the roof rail between the a and b pillar. The peak force number is the force required to cause 5 inchs of 'crush'. The amount of force required is compared to the vehicle's weight. A strength-to-weight ratio of 4.00 is required to get a 'good' rating.
      • 4 Years Ago
      Exemplary safety scores are attained through exemplary safety engineering and design procedures. It's simply costs more money to comply with these regulations. For a luxury marque to cut corners (costs) when they are charging premium price is not only unacceptable it displays a contempt for the potential consumers who are considering the brand.
      With the Hyundai Genesis sitting near the top of the competition tens of thousands of dollars less, Hyundai and the Genesis model is indeed proving, through safety, reliability, performance and equipment to be the best deal in decades.
      I would cringe if I was the Germans or the Japanese. It appears that they are gouging potential buyers.
      • 4 Years Ago
      The W212 E-Class is really shaping up to be as good as its great grand father, the W124.
      • 4 Years Ago
      Not much difference in safety among the luxury brands.
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