Facebook's data isn't as bad as you portray. Perhaps the approach vendors have these days needs adjustment. (if your vendor is running high budget dynamic ads/inventory feeds and this solely, you probably need to rethink your social strategy or choose another vendor)
Let's explain the Two types of data Facebook entitles it's advertisers to, now that Facebook incorporated a Special Ad Category, which is mandatory to submit to if your dealer is running ads through their advertising platform.
[SPOILER="Facebook's Basic Platform Data:"]Facebook's Basic Platform Data:
There's a few different data points Facebook allows it's users to use when running advertisements, which WAS traditionally the most common way to target individuals before Facebook implemented advanced audience segmentation. (Look-A-Like's & Special Ad Audiences)
Being that we all advertise dealerships & loan opportunities through the Facebook Ad Platform, we are limited in the ways we target individuals through Facebook, and this is due to discrimination law.
We may target people by:
Interests (Ex. Marketing, Small Business, Cars.com)
We may NO LONGER target people by:
Behaviors (Ex. Frequent Shopper, Administrates Facebook Page, Frequently Travels)
Age (Ex. People who are 25-40 Years of Age)
Gender (Ex. Male)
This isn't exactly crippling, as anybody using these outdated methods of targeting audiences would likely find improvement in the removal of targeting specific demographics, and the shift towards Facebook's Audience Segmentation Technology.
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[SPOILER="Facebook's Audience Segmentation Technology"]Facebook's Audience Segmentation Technology (LLA's, Look-A-Likes, SAA's):
For those that aren't aware, let me catch you up to speed on what a Look-a-Like/Special Ad Audience is:
Facebook uses many data points to segment people into "audience pools" - there are millions of them. And Facebook builds a new one just for you.. when building out a Look-a-Like/Special Ad Audience.

This may be because they're a car enthusiast, or they frequently post cat pictures, perhaps it's because they Angry React to any post pertaining to people named "Jered"? The exact specifics on how it works is UNKNOWN. However, if they meet all this criteria, they might end up in your Look-A-Like/Special Ad Audience.
For reference, this person would be in the white, along with hundreds of thousands of other individuals.
Now lets say you're acquiring leads/appointments, and out of all the leads and appointments you acquire, you sell a total of 25 New/Used vehicles thanks to the social ads you, your team, or vendor are running.
Facebook will intuitively use it's AI (I know, I hate using this buzzword) to find more individuals that fit in the white "audience pool" in the image above, based on the tracking objective you use in their platform. Acquiring more leads, and inevitably more sales for your dealer.[/SPOILER]
What we find works best:


We typically target people based on angle, using our images to narrow down our targeting. Special Financing & Rideshare being our two most popular (and successful) angles. We wrote a massively transparent tutorial on how we do this HERE.
These are the results we normally see, when running ads like we do:

