Before deciding how to pay, the best move is to discuss with the car seller how they want to be paid.
Online bank transfers are the best option to get paid, but there are other options.
Cash is an alternative, but it's worth considering that you arrange for the handover at a bank.
If the seller accepts a cheque or banker's draft, they may want to confirm with their bank that money has been transferred before they hand over the car.
No matter how the money changes hands, the most important thing is that they should provide a receipt to you.