Hi Cbonanni,
As you maybe know (and as shown in threads of this forum which are +2 years old), it used to be forbidden for a tourist to take out an argentinean registered vehicle because the Customs wanted to make sure that all the taxes, fines, whatever were paid among other reasons (and had no tool to check about that).
Now the Customs at the border have such a tool, so it's possible to take out a vehicle.
A friend of this forum (european tourist) took her car (argentinean registered) out of the country last year near Iguazu and initially had a hard time.... mhhhh very hard time... taking it out (car got temporarly seized) but finally managed to resolve the situation (she got a bit unlucky since she dealt with a "boludo" at the border).
That's how I learned about this change (don't have much time today to dig out information but will later in the week if nobody provides such links).
EDIT: quickly searched for some links but found none. If you have any doubt, you can go to the AFIP offices on Plaza de Mayo (it's a building on the right when you look at Casa Rosada). Then when you go inside, enter the rooms on the right and ask for Resguardo 1/Aduana. In this service, they don't deal precisely with such a situation (they deal with permits for foreign vehicles entering Argentina) but there's a very, very helpful lady (dark hair, dark skin) whose name is Angie if I recall => she should be able to provide you a confirmation (obviously, in doubt, better lose one hour in BA than a whole day at a frontier).