I talk to others about FB marketplace a lot and many have positive information. My experience is not so good and I think FB holds the record for the most scammers of all selling venues.
Almost all selling venues have been "polluted" by scammers, and sorting through the wheat from the chaff is challenging and annoying too. Craigslist went down the toilet years ago. OfferUp much the same. I don't do FB but I've heard from others that it's full of scams and scammers. The only one that was reasonably secure is eBay. I've sold over 1,000 items (not commercially mind you, just "stuff") over more than 20 years, and can count the bad experiences on one hand. Most of those were international so I sell only in the USA now.
The latest scam, however is all about eBay. It works like this: a hacker finds an eBay account that has NOT listed anything for sale for a while, and hacks into it. Rather than make a for sale posting by auction or fixed price, they use this new and obscure eBay selling by "classified listing". They then post a highly desirable and in-demand product at an exceptionally low price. The only way to buy the item is for the BUYER to provide personal details to the SELLER. The seller, or the scammer as the true seller doesn't even know what's going on because they haven't been to eBay for a while, gets buyer's information and asks you to send them money. Once that's done, you have been scammed. There is no product, the money is gone, and eBay has warned you that all dealings are OFF PLATFORM.
I have not been scammed, but have seen at least 10 of these scams run and have reported them all to eBay. More often than not the item disappears quickly.
But back to that car, yes I think the mileage is wrong! Why not listed here? The seller may not even know of our existence.