Cooley On Cars
Smarter Driver: Understanding crash safety and car sizeConventional wisdom holds that tiny cars have bigger risks in a crash. Yet a Chevy Spark has the same crashworthiness rating as a 1,000-pound heavier Honda Accord Coupe -- so what's the real story behind crash safety and car size?
-The "big car is safer" concept needs a little nuance. There's weight, proportions, engineering, and technology. Weight is obvious. A small car has less mass to resist being accelerated, in other words, drop-kicked by the bigger car it collides with. That, in turn, means things inside the small car may be more violently accelerated as well. Then, there are proportions. A small car means less car around you, front and rear in particular. That gives engineers less room to create crumple zones that dissipate the force of an impact into the bending of metal instead of the bending of you. Up next is engineering. Sophisticated design has overcome some of the weight and proportion disadvantage. Hence, some small cars get better crash course than bigger ones. Key is structural integrity, to reduce or prevent intrusion into the passenger cabin of either the other car or parts of your own car. And finally, technology. It used to be that small cars were cheated of things like anti-lock brakes and airbags and stability control. Today, all of those are on virtually every new car and more advanced tech like pre-collision braking and airbags in exotic places are no longer just the domain of the $100,000 Mercedes. Now, most recently, the IIHS found that only one of the 11 minicars tested were able to get an acceptable rating in the new small overlap crash test. Given how important such ratings are in the showroom, expect the engineering and technology folks to at least narrow the gap on this lousy performance. -A small overlap crash can be devastating because often the main structural elements of the vehicle are bypassed. If the vehicle is not designed for this, it can lead to a massive collapse of the occupant compartment and a big reduction in survival space. -It pays to double check how a car you're considering really does in crash tests and not just rely on conventional wisdom.