There is a saying in the legal world-- that "possession is 9/10's of the law."  This means that if you are caught in possession of stolen property that you can be charged for receiving or possessing that property.  This is certainly enough probable cause for the officers to make an arrest.  The issue, however, will be, "is it enough for the jury to find her guilty."  Considering that she was not the owner of the vehicle and she may not have had any reason to believe that anything was stolen, she would have a decent defensive theory to present to a judge or jury.  Considering the nature of these facts, it would really help if she hired a criminal defense attorney.  If she cannot afford an attorney, she needs to request a court appointed attorney.