IMO, and I am no where near being a lawyer...

She was arrested and charged with attempted kidnapping, battery, attempted vehicle burglary with battery, and destruction of evidence. I think you can assume that through the course of normal investigation her car would have been found and searched. Probable cause would be established from the fact that she (most likely) used the car to get to the crime scene. I see no statement on what might have been in plain view which would have caused the police to open the trunk but I think that is easy to get around with the charges above. Her statement may of aided the police in getting to her car quicker but it was not the one and only means of finding the car and the items inside....again normal police investigation would have led to the car eventually. With my assumptions above, the search of the car should be legal and therefore, the items found should be used for/against her case.

Now the admissibility of her statements and the fact she may have waived her Miranda rights are a whole other story.