FCR is the right to bring a car in as a Tunisian abroad after a certain period.
RS is the designation on the numberplate where that is used upon.... and thus when done can only be sold to another person in that situation.
Back in the day people would offer their FCR for sale to save money.
My points as I tried this years ago.
It's one of the most problematic and open to corruption procedures in Tunisia even if you have the right.
You have to make sure you have the right and this is done via you passport stamps
You have to choose a relevant vehicle of a certain age.
Insurance is a pain for them sometimes compared to Tunisian vehicles.
RS cars devalue faster than Tunisian registered taxed cars and the latter you can sell to anyone in Tunisia after.
When I tried this I bought my wife a lovely golf plus form Germany and after a few weeks of paying xxx dinars here and there I just got annoyed and sold it to another x pat and bought a Tunisian registered car.