foreign plated cars and migratory status changes

When Tom and I moved to Merida in 2006 we brought with us a car. Here it is a 'foreign plated car'.  The rumors speculation and fear about having a foreign plated car are incredible.   The car comes in attached to someones migratory document. In our case my FM3.  Rumors and speculation abound about how long you can keep a foreign plated car, and what happens when your migratory status changes.  For example when I changed from FM3 to FM2 It was rumored and speculated that I had to get the car out of the country.

We made a trip to Aduana, with a friend that is Mexican to act as translator.  We were told that as long as my migratory documents was up to date I was good, but that I needed to notify Aduana of any changes to my migratory documents.  I was given text for a letter advising Aduana of the change in migratory status.  I keyed the text along with the particulars about my migratory documents in to a letter and sent it off. I kept a copy that resides in the car.  I never received any acknowledgment of receipt of the letter, but was told it didn't matter.  ni modos!

So now I have my Residente Permanente card, just another change to my migratory status right!. Now again the rumors and speculation have started, what do we need to do, we can only keep foreign plated cars 30 days, we have to do this, we have to do that, blah, blah,  blah.   So what am I doing?????  I used the same form letter as last time, changed the data to reflect the current change to my migratory document and have an envelope with the letter  ready to post to the Aduana. I have a copy that resides in the car.

So for those of you interested here is the text of the letter:

Merida, Yucatan,  DATE

Administracion General de Aduanas
Av. Hidalgo 77, col. Guerrero,
c.p. 06300, México, D.F.

A quien corresponda,

Por medio de la presente, notifico que me otorgado un permiso de importacion temporal numero ####, con un documento migratorio FM3 de No Inmigrante rentista numero ###### y el DATE obtuve un cambio de calidad migratoria y ahora cuento con un documento migratorio  Residente Permanente numero #######.

Manifesto bajo protesta de decir verdad que persisten las condiciones bajo las cuales seme fue entregado el permiso.

Sin mas por el momento, agradezco la atencion prestada.


more or less it says this

To whom it may concern,

Through hereby notified that I granted a temporary import permit number #######, with an immigration document FM3 de No Inmigrante rentista numero ######## y el DATE got a change of immigration status and I now have an immigration document Residente Permanente numero #######.

I swear under oath that these are conditions under which the permission was given.
No more for now, thank you for your attention.