Car insurance and permits
While some U.S. insurance companies do extend their comprehensive and collision coverage into Mexico, none of these offers Liability coverage in Mexico, which is required by law. You can purchase Mexican Insurance online prior to travel, as well as over the phone or at numerous spots along the drive down (for example in Ajo, Why, or at the gas station in Lukeville just before crossing). You do not need a vehicle permit for travel to Rocky Point though you will need to have: valid Mexican insurance for the period of your stay, car registration, valid driver’s license.
If your travel plans in Mexico include driving solely within the state of Sonora, you will be happy to know about the Only Sonora program (unique in Mexico), which allows Americans to visit Sonora without paying the customary federal vehicule fee when crossing at any of the 5 border crossings in Sonora: San Luis Rio Colorado, General Plutarco Elias Calles (Sonoyta), Nogales, Naco, Agua Prieta, or through the port in Guaymas.
If you plan to travel further into Mexico (or rather out of the State of Sonora), you may temporarily import your vehicle for a period of 180 days with less paperwork and at a lower cost than before. These requirements include:
Documents
• Current license plates
• Valid vehicle registration or title, with current insurance
• Passport or residency credentials, with valid immigration permit (FMT, FM2, FM3, or FME as applicable)
• Driver’s license
Costs
Cost for permit valid for up to 6 months
Payment at Banjercito: $22.00 DLS, plus tax *When paying in Mexico, this must be done in pesos.
Payment at Mexican Consulate in US (for example Phoenix, AZ): $36.00 plus tax
In any case the vehicle must be driven by the owner, his/her spouse, family or siblings (who are also foreigners or Mexicans residing abroad). If the vehicle is driven by someone else, the owner of the vehicle must be on board. (Information retrieved Oct. 31, 2011 from: GoToSonora)
While this service used to be available at the border, you now must get this at the customs check-point along Highway 2 heading South to Caborca. In order to acquire the car permit you will need the original and a copy of: the car title, your valid visa (from immigration), a driver’s license, passport, or copy of your birth certificate, and a valid credit card. If you prefer to pay in cash you will be asked to leave a deposit at the border. After visiting Mexico, you must check in at the border so that the permit may be taken off your car by the designated officials. This will also guarantee that you will not be charged for not re-entering the US.