Hi,
Why would anyone want to receive money via paypal for the sale of a car? the
seller will have to pay paypal their fee, so cash on collection os much better, or is the seller trying to do a dodgy deal? I would look into paypals help pages and see what the situation is if you get a bad deal, but, be careful, read the small print, the car could be advertised as this that and the other, but may have other problems, but the advert may have stated this, if you had read between the lines. on the other hand, the seller may not want some dodgy dealtype turning up and trying to bid them down, as happens in many cases, it has happened to me twice, so it may be genuine.
no real answer here, play it by ear.