The Nissan Altima parked in a parking lot less than a mile away from where she lives.
The death is under investigation, authorities do not suspect foul play.
Police say Joseph was last seen leaving her home in Syosset on February 24.
Her parents believes she was attending classes at the New York Institute of Technology in Old Westbury, officials said. However, the school says she had not been a student since May of '13.