Long story short, decided recently to donate my old car to charity (Vietnam Veterans of MA). A number of charities up here work with the car auction houses (some of those are huge), and the buyers bid on them. Some buyers (usually dealers, but others, too) buy the cars for repairs they know are needed--so they can flip for a higher price to sell; some are bought just for parts; and some go to salvage places and sold for the metal. The auction houses get a percent of the sales, and the charities get a percent (varies how much, depending upon various deals each has set up).
Good thing is that the auction places tow the car away for free, so that's helpful, particularly in the case of a car you know you can't sell for much anyway.
Then, of course, there's the social sideshow going on in the driveway, between tow driver and hubs. Guys just love to talk about cars -- old cars, new cars, cars that work, and cars that don't.
Hubs enjoyed helping the guy push the car (big fun
) on to the rear hitch (truck was a very long flatbed with one car already on top of it). Ours was dinky -- so the tow guy set it up for towing, hitched up to the back of this large truck, with our car's back wheels on the road. (Man had to haul both cars to the MA/NY border.) It was the highlight of hubs' morning.