I arrived in Guatemala City a week ago. Two days ago I was stopped at a routine traffic checkpoint where I presented my US driver's license. The officer informed me that I am required to carry my passport with me while driving, to show my date of entry into Guatemala, because I am only permitted to drive with a foreign license for 30 days. I was not fined, rather only told to carry my passport in the vehicle in the future.
U.S. driver's licenses may be used in Guatemala for a period of thirty days.
So the officer was right.
Anyway, according to the same page, you have three options to drive there after the thirty days:
International Driver's Licenses:
We understand that Guatemala recognizes the International Driver's License, which is available in the United States through chapters of the American Automobile Association (AAA). When driving with an International Driver's License, a valid U.S. state license should also be carried.
Temporary Driving Permits or Permisos:
The Guatemalan National Civil Police can issue temporary permits or permisos to foreigners who hold valid driver's licenses from another country and who need to drive in Guatemala beyond their initial thirty day period in the country. Such permisos cost Q30 per month of validity, and may not be issued for a period in excess of the applicant's authorized stay (i.e., the term of their visa) in Guatemala. There are tramitadores in Guatemala City and elsewhere who may be able to assist an applicant in obtaining such a permiso. When driving with a permiso, one must carry one's valid foreign driver's license in addition to the permiso. Permisos can be obtained at:
Departamento de Transito
Galerias del Sur
Calzada Aguilar Batres 34-70, Zona 11
Tel. (502) 2320-4545
Guatemalan Driver's Licenses:
At the present, we have been advised that the Department of Transit of the National Civil Police will only issue Guatemalan driver's licenses to persons who are properly documented as residents of Guatemala. Persons who have applied for Guatemalan resident status, but who have not yet been granted that status, are not eligible for Guatemalan driver's licenses. When applying for a Guatemalan driver's license, in addition to the application form, foreign residents of Guatemala need to provide the following documents and information to the Department of Transit: (i) six cedula-sized photos; (ii) the applicant's blood type; (iii) whether the applicant is allergic to penicillin; (iv) a photocopy of the applicant's passport or cedula; and (v) a valid foreign driver's license (to avoid having to take the written and driving tests again). An applicant will also need to submit to a vision exam.