I believe that in order to do a wire transfer, you need to give your account information to the other party.
Only if he is paying YOU to buy HIS car.
The BUYER (you) needs the SELLER'S account info to give to YOUR bank so the money goes from the BUYER'S account (yours)to the SELLERS account (his).
He knows nothing of your account numbers or information.
It sometimes takes an hour or more for the transfer to clear the Federal Reserve Banking system. I thought it was an instantaneous transaction. In my sale, the buyer called his bank (Chicago) and said go ahead with the transfer (after he inspected the car), 15 minutes later I called my bank Virginia) to see if the funds were in my account, NADA. He then called his bank back, and they assured him that it was done, but that it then has to clear the Federal Reserve (they make sure that the funds are good and to make sure that no fraud or banking laws are violated I guess). My bank verified this fact also and about 90 minutes later the funds were in my account.
I didn't want any kind of check (even a bank cashiers check) due to the fact that they can be forged, OR at the time of checking the authenticity of the check, they are good with funds in the account, but when it goes to through the banking system 4-7 days later, there are NO funds in the account, and you are hung out!
IMHO, for a BUYER, a wire transfer is THE BEST way to complete the transfer of funds and the sale.