Paypal is expensive and the buyer needs to collect the car anyway. Lots of reasons for cash type money, like it is simple and it works, as does getting on with it. Sadly this guy sounds like he has had the same sort of goners I have, who have difficulty in actually buying anything when it comes down to it. The more ways that are created to communicate and pay the more these sorts cannot raise the money or liaise for logistics. Treat them with the short shrift the deserve and hopefully they will go and annoy someone else.
I have just had to seize and resell two items from deposits of 15 months and 3 years respectively, due to no action, no coms, from the other side. No doubt there will be tears before bedtime and they will want their deposits back shortly when they realize they have lost out. Several more outstanding and I cannot, or see, why I should wait any longer, as this stuff is in the way now I am starting to move. That is ignoring the money tied up I cannot use.
Other folk happily do a deal, agree a timely arrangement, and get stuff sorted between us in good order over a few months. No probs.