This plugin is a must when working with custom post types.
Let's say I create a custom post that represent a car, I add an attachment box to let my user upload pdfs for specifications. I can choose how this will be displayed on the page, just as the client want! I could add pictures that will go in a predefined picture slider, etc. and then I decide how it will show on the single-car layout or wathever. Amazing work, thank you so much for this swiss knife upload plugin!!! :D
PS. I did not use this for cars, but you see the point here. ;)