The process of going through divorce and equitable distribution is the mechanism to resolve these kinds of economic issues. You should sit down with a family law attorney to discuss your specific situation and the rights and remedies available to you.
First, you should retain an experienced family law attorney in your area to discuss your options for retrieving your personal property. Often, with the involvement of the attorneys you will be able to work out an agreement for the vehicles to be distributed. If she does not have an attorney or she refuses to be reasonable, you have other options such as court intervention, but a divorce action needs to be filed. In some counties, the Judge will not get involved in these issues so your attorney will be able to advise you accordingly.
My response is based solely on the limited information contained in the question. It is not meant to substitute your attorney's advice.
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