Bet you never considered this one! When a vehicle is damaged, most people assume their insurers will pay for it to be repaired with identical parts that come from their car's particular manufacturer, also known as "original equipment manufacturer" (OEM) parts. That's a risky assumption, though, as the parts used in the repair may instead be "aftermarket" parts, which are car parts made to fit a general type of vehicle, but not specifically for a particular make and model. Aftermarket parts are less expensive, which is why some insurers prefer to use them. And while certain states specify insurers must cover OEM parts, others don't. To further complicate matters, some insurance companies use both kinds of parts. They'll spring for OEM parts when it comes to safety items like air bags, for example, but use aftermarket parts for less-critical items like door handles and fenders.
If an insurer only covers aftermarket parts, it doesn't mean you have to rule them out, especially if their rates are good and they have a solid reputation. Maybe you don't even care. And if you do, you can always opt to pay a little extra to upgrade from aftermarket parts to OEM parts if you find their overall rates attractive. It's just best to know their policy ahead of time [source: Jones, Zeman].