GENERAL REQUIREMENTS:
You will need a valid driver's license; those issued by most other countries are recognized by the Mexican Government. This is all you need to drive in Mexico (besides insurance). Mexican driver's license's are not issued to people with a FM-T. A FM-3 or better is needed for obtaining a Mexican driver's license.
You will also need proof of citizenship to get back into the U.S. Your driver's license isn't considered proof of citizenship so you will need one of the following:
. Certified Birth Certificate, sometimes titled "Certification of Live Birth' or something along those lines; this is NOT the one with your footprint on it that is handed out by some hospitals. And a picture ID (such as a drivers license or one of the below); or
. Valid Passport (more on this below); Or
. Valid Military ID card; Or
. Certified Certificate of Naturalization.
You will also need a valid registration for all your vehicles. The registration must be in your name.
If there are lien holders on the vehicle(s), you will need a letter from the lien holder authorizing you to take the vehicle across the border. This includes trailers, boats, boat trailers, and ATV's & motorcycles above 500 cc. Each driver is allowed only one vehicle above 500 cc (excluding the new RV sticker; see 10 Year Permits for RV's).
You will need insurance, and for that you will need at least 3 copies each of all of the above. You will be required to show for inspection, the original and leave a copy of these at various places. Normally it is one copy for the Migración office and one copy for the Banjercito (bank). In some cases you might have to go to two different windows at the Banjercito, one for the FM-T's and one for the vehicle stickers, and both will ask for copies; hence 3 copies.
You will also need copies of the paperwork you are issued. There are copy centers co-located with the Banjercito's, where, for a nominal fee, you can get these documents (and any that you didn't bring copies of) copied.
Finally, to get vehicle permits, you will need a valid U.S or Canadian credit card. If you don't have one, you will have to post bond on all the vehicles. This is expensive and complicated, and is based on the value of the vehicle. If you're going this route, check with the local Consulate ahead of time.
