You need to do exactly the same as if you were selling the car in your own state-ie give a receipt and complete the relevant section on your rego document-it is up to the buyer to do the rest. I bought my Freelander across the border from the ACT in NSW.n NSW on the back of the rego papers is a section you fill out with the new owners details and also a section notification of dissposel of the vehicle that tears off, you then send that off to the RTA. There could be a seperate form now, that needs to be filled in, that's for NSW anyway.