"Aftermarket" is a term used to describe accessories that are not made by the factory. So for example, for your Saturn Outlook, if you buy accessories for your car that are not actually made by Saturn, then those are termed "aftermarket". Many people use the term "Outlook aftermarket accessories" specifically when referring to custom accessories for the Outlook, like performance accessories or custom appearance accessories. But even if you just replace your Outlook brake pads with OEM-grade factory-style brake pads that are not made by Saturn, those too are aftermarket Outlook accessories. Over the course of a vehicle's life, it almost certainly will have aftermarket accessories installed in it at some point, even if the vehicle is never actually "modded out".