The thing is first of all they do not allow own Cars if you are a permanent resident/about to land. In case if you are bringing your own car they expect you to be ready with export-import papers to be done during landing. If it is a rental car they do not care as you are anyhow going to return it either side. Before they allowed own cars with a Warning(cannot bring own cars unless you import) but may be because of new restrictions in place they are strictly saying NO to it i guess.
Also if you are planning to softland , its highly recommended to try it with a Rental car. Because softlanding is itself not in their rule books. Its totally based on discretion of officers.