Nuevo Leon plates, that correspond to the state where Monterrey, Mexico is
The numbering for cars consists of three letters, and four numbers always.
About a year ago all plates started with R, to the point where numbers ran out (RZZ-99-99).
The new plates start with S (SAA-00-00). Because license plate designs change in each State of Mexico when a new state government comes in turn, the numbers change alot, hence plates starting with RAA, date back decades, and are no longer seen.
Plates for pickup trucks and other cargo vehicles start with a P, and contain another letter and five numbers. In this design that came out in 2004, there is state propaganda in the bottom left corner that say "Nuevo Leon, Estado de Progeso" which translates into "Nuevo Leon, State of Progress". We also have, like in other countries, stickers that certify that taxes (tenecias) are paid. Additionaly, there is a sticker that has to be posted on the car windows, that is a small, identical, copy of the license plates.
Old Nuevo Leon designs:
In both these designs there is a drawing of one of the landmarks of Monterrey, the "Cerro de la Silla", a mountain that has the shape of a horse saddle. These two designs are from past State goverments.