Intra-bank transfers are instant, so is PayPal/Revolut/Zelle or whatever else, and many inter-bank transfers are also instant or very nearly so in the EU. None of these, except maybe cash, protect you from someone sinply not delivering the physical good (car + car keys) after the transfer completes.

From a legal standpoint, the bank transfer speed is anyway irrelevant - you first sign a sale contract that makes the car yours and the money theirs, before anything actually exchanges hands. If one party fails to deliver the money or the other fails to deliver the good, they are anyway liable. With instant transfers, the buyer is more likely to get scammed; with delayed transfers, both the buyer and the seller are equally as likely to get scammed - that is the only difference.