"A recent test conducted by the Certified Automotive Parts Association shows why it’s important to make sure you get automaker-certified replacement parts after an accident. The video shows a last-generation Ford Fusion front bumper in a 6.1 mph collision, the aftermath, and then another collision using a replacement bumper for the car from a third-party supplier.
The stark difference is due to the plastic materials that make up each bumper. The Ford is a composite of polycarbonate polybutylene terephthalate, or PC/PBT. It’s is a relatively elastic plastic that can deform and bounce back to its original shape. The knock-off is made of acrylonitrile butadiene styrene, which is brittle. The knock-off bumper uses a non-spec plastic despite having the words “PC/PBT” disingenuously printed all over it.
The outcome is that the aftermarket bumper will not perform the safety function it was designed to perform — namely, to protect a vehicle from structural damage in a low-speed impact and to cushion the blow to passengers in a high-speed one.
CAPA blames the above incident on a lack of standards in the aftermarket parts business. Non-manufacturer-built replacement parts became popular in the 1980s as auto insurers looked at third-party parts as a relatively cheap way to keep costs down, CAPA says. Some insurers have since then suspended the use of third-party bumper replacements in light of the study."