You need to be able to prove that you are genuinely moving to the State and that you have used the car legally in your original location. The exemption is for a transfer of permanent residence and so documents such as the sale/purchase of property, termination and commencement of a tenancy, termination and offer of employment, insurance records, service records may all be required.
You may not be required to produce these depending on the VRT office, but I wouldn't rely on it.
If you can prove your case then you shouldn't have a problem.
SSE