Unless you are absolutely certain about the identity of the driver, you would be reckless to allow him/her to sit there for hours on your driveway. With recent stories about home robberies and carjackings of yidden by individuals dressed in yeshivish lvush etc. why even take a slight chance and risk your safety and that of your family?? If the unknown driver doesn’t move immediately, call the police.
P.S. I will be glad to provide a heter for any concerns about mesirah
