Rust cuts deep—literally, according to a new study conducted in Sweden. Cars that show merely superficial rust may be considerably more dangerous in the event of a crash.
The insurance company Folksam and the homeowner organization Villaägarnas Riksförbund of Sweden performed crash tests on a handful of used Mazda and Volkswagen cars that showed signs of typical rust. The results they released earlier this month show a major degradation in the cars' safety structures.
The Swedish firms subjected Mazda 6 mid-size cars and Volkswagen Golf hatchbacks to the same kind of crash-testing that would have been performed when they were new cars about 15 years ago.
In the videos they released, the Mazdas' rusty rocker panels crumbled in both the frontal and side-impact collisions. Researchers noted that the cars' chassis rails separated from the floor, their footwells ruptured, their sills gave way, and the driver and passenger-side seat mountings moved when they should have remained stationary.
Folksam said that the chance of a fatality increased by as much as 20 percent because of the weakened structure caused by corrosion largely invisible at first glance.
The Golfs fared better in the barrage of tests, in part because of superior rustproofing when they were new. However, they still showed some signs of weakened structures even though their rusty panels were not as immediately visibl..
Folksam pointed out that rust is usually more than a cosmetic concern and should be taken seriously to help assure crashworthiness.