Can you tell me more about how to interpret safety ratings? The A3 is an Insurance Institute for Highway Safety Top Safety Pick, but does that only mean within its class? Also, the BMW 3 Series fared poorly in rear collisions, but the front-impact cabin intrusion numbers were better than the A3’s. Since the figures are summarized to very basic scores and are compared within car classes, it’s hard to really understand which is safer, and if the difference is meaningful.
Even though the BMW 3 Series scored better than the Audi A3 in one category, the A3’s overall score and Top Safety Pick status still make it a preferred model to the 3 Series when it comes to safety.
IIHS spokesman Russ Rader explains:
“The institute's frontal crash test is a high-speed test, so it's unlikely a person in a real-world crash of similar severity could walk away uninjured,” he said. “The goal is to limit the severity of the injuries. It's best to look at a vehicle's overall ratings in all three tests because no one can predict what kind of crash they're going to be in. The A3 and 3 Series are both midsize cars of similar weight, so the crash-test ratings are comparable. The A3 is a Top Safety Pick, earning Good ratings in all three institute tests, while the 3 Series is not. For people comparing these two cars, we would recommend the A3 for its superior overall ratings.”
As Rader mentioned, IIHS awards Top Safety Pick status to any car that scores Good in the institute’s frontal-offset, side-impact and rear crash tests. IIHS rates performances as Good, Acceptable, Marginal or Poor. A standard electronic stability system is also required to gain the Top Safety Pick title.
You should, however, avoid comparing safety ratings of vehicles in different classes or vehicles that have significant weight differences. Your comparison is good, though, as the A3 and 3 Series are comparably sized.
The Cars.com safety article “Crash Tests: What You Need to Know” explains why you should avoid comparing safety ratings between different classes:
“Model-to-model comparisons of frontal crash-test ratings are valid only within a vehicle class or between models of comparable weight (within 250 pounds). The test reflects how the vehicle would fare in a collision with another of the same model, not versus a larger or smaller vehicle (or a lower- or higher-riding vehicle). A heavier vehicle would protect its occupants better than a lighter one if all other factors were equal, but they never are. So a large vehicle with a Poor rating is not necessarily safer than a small vehicle with a Good rating. Unfortunately, researchers have not yet devised a reliable method for reporting the effect of size differences on a vehicle's score.”
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