Hi,
@Dharshini were you able to have any success with your process?
I'm unable to find any information regarding the export of vehicles from Sri Lanka except for an article dated in 2018 about tax incentives for re-exports of cars older than 5 years. [1]
The general messaging is 'No' from most people I've spoken to but the RMV isn't too sure about the process too AFAIU.
[1]: https://economynext.com/sri-lanka-to-encourage-re-export-of-used-cars-6235/
Cheers!