Why crash testing is important, even with death rate data

Some vehicles have more deaths than others for the same amount of registered vehicle years, and this discrepancy boils down to two things: how safe the vehicle is in a crash, and the types of drivers who are driving them. 

The report I linked to in the first paragraph looks at death rates for 2001-2004 model vehicles, a period of time where there was significantly more variation in crash test results than there is today. The Chevy Astro and 2-door, 2WD Chevy Blazer were the safest and deadliest vehicles, respectively. The average number of deaths was 79 per million registered vehicle years; the Astro had 7, the 2-door Blazer had 232.

For the Blazer, it makes sense: the Blazer did poorly in the IIHS frontal offset crash test and had mediocre NHTSA crash test results, as well as a high likelihood of rolling in a crash. But adding a set of rear doors nearly halves that death rate to 123. While still significantly higher than the 79 average, the four door model is more staid and less likely to be driven by high-risk drivers. 

The Astro had poor crash test results as well, similar to the Blazer. However, the Astro is larger than a Blazer, and thus comes off better in a multiple vehicle crash, as well as attracting a very safe cohort of drivers relative to the average. 

Nevertheless, the Astro is an exception to the rule: most of the safest vehicles had good crash test ratings, while most of the least safe vehicles had poor crash test ratings or were unrated. 

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