The Insurance Institute for Highway Safety’s small overlap crash test is no joke. Vehicles that pass often include provisions specifically for the test, and those provisions add weight. How much? Well, according to Porsche’s SUV Body in White Team Leader Rudiger Jahn, 110 pounds in the case of the new Cayenne.
We all know that designing cars to pass ever-stricter crash tests means adding either cost or weight (or both). Exactly how much a specific crash test—particularly the most difficult one, the small overlap test (which involves a vehicle crashing only one quarter of its frontal width into a barrier)—adds in weight has been a mystery to me. So to actually get a figure is something I found rather interesting. One hundred ten pounds is a significant figure, even for an SUV. That’s like having an overweight golden retriever in your car at all times.
At a press event near Duesseldorf, Jahn walked me around the new 2019 Cayenne to show which provisions had to be added for the small overlap crash test. The first, he told me, was steel bolstering in the wheel well to reduce intrusion into the driver’s footwell:
The second provision was a diagonal member that ties that bolstered wheel well structure into a central longitudinal beam. The idea is that the energy from the crash that pushes the inside of the wheel well will be transferred through that diagonal member, into the strong longitudinal beam, reducing intrusion.
In addition to the provisions on the body, Jahn also said the front subframe was designed in such a way that it precisely orients the wheel during a crash to help minimize intrusion into the cabin. If you look at the vehicles that pass IIHS’s rigorous test, you’ll notice that they all turn the driver’s side wheel in a particular way; here’s an example showing the 2018 Volkswagen Atlas:
So yes, the small overlap crash test added 110 pounds to the new Cayenne. But that just meant Jahn and his team at Porsche had to find clever ways to cut weight elsewhere, and they succeeded—the new Cayenne weighs up to 143 pounds less than its predecessor thanks to a body made largely of aluminum. (I’ll delve further into the nerdiness that went into that in a subsequent article).
I reached out to IIHS to learn more about how their small overlap test affects vehicle weight, and their representative told me:
When we’ve looked at weight changes, we haven’t seen a consistent pattern...The 2014 Nissan Rogue, for example, improved to good in the small overlap test compared with the 2013 model’s marginal rating. However, the 2014 model was a redesign and the vehicle got a little larger. We don’t know how much of that weight increase had to do with changes for the small overlap test. Other vehicles with improved performance lost weight. Manufacturers that integrated structural improvements into new designs were less likely to have weight increases compared to those that decided to make “band-aid” changes with add-on parts that can be bulky and require additional assembly.
Here’s a slide showing how much weight some car models gained and lost between generations that weren’t designed for the small overlap crash, and those that were.