Legal Question in Real Estate Law in California

Automobiles are "personal property," not "real estate and real property" so your question is in the wrong category, but I'll give you my opinion anyway. You should review your sub-lease agreement, probably with an attorney, to see if it has been violated. It probably has, since you probably haven't received timely rental payments. Then, you should invoke the cancellation provisions of your sublease (if you can). This probably means sending a cancellation notice to the address given in the sublease. When she doesn't respond, report the matter to the police. I would avoid saying it is stolen, although by now the sublessee may be committing some crime by not staying in touch (embezzlement?).