The Insurance Institute for Highway Safety (IIHS) looked into the question. It makes sense that you would be at some additional risk when riding in a convertible vs. a hard-top vehicle. The roof structure appears quite flimsy, doesn’t it?
The head of statistical services at the IIHS compared data from the Fatality Analysis Reporting System (FARS) maintained by the National Highway Traffic Safety Administration (NHTSA). This is essentially a collection of police reports of fatal crashes from all across the United States. Information about how many fatal crashes police have reported comes from two analysis systems kept by NHTSA.
The statistician compared the rates of driver deaths and crashes per miles traveled between convertibles and non-convertible versions of the same vehicles. These were all between one and five years old when the crashes took place, which was during 2014-18. Interestingly, he found no statistically significant differences between the convertibles and non-convertibles.
Then, he dug into factors like driver behavior, point of impact, seatbelt use, impairment rates and whether the driver was ejected from the vehicle. (Being ejected from a vehicle greatly increases your chance of being seriously injured or killed.)
Here, he did find some differences. It appears that drivers can be ejected from convertibles more easily than they can from hard-top vehicles of the same type. At the same time, however, he found that convertibles were actually involved in 6% fewer crashes per miles traveled. The death rate among drivers was actually 11% lower as a result.
Convertibles are exempt from NHTSA’s roof-crush resistance standards
NHTSA exempts convertibles from its roof strength tests. That said, in 2009 the IIHS added a roof-strength evaluation to its crashworthiness testing program. In order for a car to be labeled a “TOP SAFETY PICK” by the IIHS, it has to pass the roof-strength test.
Perhaps as a result of this requirement, some manufacturers have voluntarily strengthened their convertibles’ roof structures to provide additional protection in the case of a rollover.
Convertibles have lower fatal crash rates overall
It’s true that drivers are more likely to be ejected from convertibles. In ordinary crashes, 21% of the convertible drivers who were killed were ejected, versus 17% of the conventional drivers. In rollovers, 43% of the convertible drivers were ejected versus 35% for conventional drivers.
Convertible drivers were slightly less likely to speed than conventional drivers, slightly more likely to wear seatbelts, and somewhat more likely to be alcohol-impaired. This indicates that drivers behave somewhat differently when driving convertibles.
Although it wasn’t possible to analyze all the ways convertible drivers behave differently from conventional ones, it was clear that there was little statistical difference in the fatal crash rates.