Whether or not there is a probate estate, title can be passed to others by submitting the right forms with the Pennsylvania Bureau of Motor Vehicles. (Procedure in other states may be different.)
Form MV-39 contains detailed instructions on what you will need to submit, which varies depending on how the car was titled.
Keep in mind that to pass title using that form, all of the deceased person’s debts must be paid and you will need to submit proof of death (either an original death certificate or the certification of an attending physician or funeral director on the Form MV-39).