I generally dislike Facebook for just about everything except Marketplace. All the brand specific groups ask the same questions over and over again. There's no way to effectively search previous questions, etc.

Lost Muscle Cars is one of the better places to find your old car on Facebook. Some interesting stories come out...

The only thing I don't like is he doesn't allow searches for previous owner information of a car you currently own (although one of those was posted this morning)

If anyone owns or knows of this car, the previous owner is trying to find it:

 

As opposed to on a forum like this?

 

At least here you can easily show a link to a previous thread.