Heavier Cars are Safer

My dad used to tell me that heavier cars are safer, but he didn't have data to back up his claim.  There's an excellent article on Edmunds.com about the relationship between vehicle size, age, and safety.  They used data from IIHS, which publishes driver death rates by make and model.  This data is a better predictor of safety because it relies on real-world statistics rather than artificial crash tests.  A crash test attempts to predict what will happen, but IIHS has historical data that shows what really happened.

In this post, I add another variable that is missing from the IIHS data: curb weight.  I got the curb weight for each model from Edmunds.com, which provides easy-to-manipulate URLs in the following format:

https://www.edmunds.com/{make}/{model}/{year}/features-specs/

then search the page for "curb" to quickly find the curb weight.

Below is the resulting scatter plot of curb weight versus driver death rates:



You can see by looking at the plot that heavier cars generally have lower driver death rates, and a trend line automatically generated by Excel (not shown above) shows that one fewer driver dies (per million registered years) for every seventeen additional pounds of weight.