I've had some luck with tracking down rego history of cars . First you need to find out if there is any records of the car .Roads departments can usually can give you yes or no answers . So just ask if there's any record of your car. You might have to ring a couple of times to find a operator that's willing to help . Once you find someone willing to help they can access archive files if the car hasn't had registration for awhile . Then you just need to submit a request for access under the freedom of information . You can ask for any information you like . If you want previous owners they have to send a request to the owner to make sure they can give that information out.

Hope this helps