1. A VALID DRIVER'S LICENSE, issued outside of Mexico. 
2. YOUR CURRENT CAR REGISTRATION AND A COPY OF THE ORIGINAL CAR TITLE. If the registration or title is in more than one name and not all the named people are traveling with you, then a notarized letter from the absent person(s) authorizing use of the vehicle for the trip is required; have it ready just in case. The car registration and your credit card (see below) must be in the same name.
3. If your car is financed, is a rental, is leased, or if it’s a company car, you’ll have to submit a notarized letter of permission (remember the word Apostille here) from the lien holder or lending institution.
4. A VALID INTERNATIONAL MAJOR CREDIT CARD. With a credit card, you are only required to pay the car-importation fee of approximately $30. The credit card must be in the same name as the car registration. If you do not have a major credit card (Visa, MasterCard, American Express, or Diners Club) you will have to post a bond or make a deposit on the vehicle.  The amount of the bond is determined by the vehicle’s year and model.  It is refunded when you reenter the U.S.  In order to recover this bond or avoid credit card charges, travelers should return to the same Mexican customs office they entered through. The permit is valid for up to six months and the vehicle may be driven across the border multiple times during the authorized period of the permit. 
5. YOUR ORIGINAL IMMIGRATION DOCUMENTATION.   This will either be your tourist permit (FMT), FM-2 or FM-3 visas.
6. YOUR  TEMPORARY IMPORTATION APPLICATION. This is another form, one that assures the government of Mexico that you are only importing your car for your personal use and that you won’t be selling the car in Mexico. 

All forms will be copied either at the border for a fee, or you can bring copies for the border officials.

Once you get your permit, keep it on the windshield at all times.

If you decide to stay in Mexico on an FM-3 or FM-2 visa, your automobile is allowed to stay as well.  However, it must be re-registered yearly, when you renew your visa.

AN IMPORTANT NOTE:  The person (or relative of the person) whose name appears on the permit must always be in the car while driving in Mexico. Violation of this rule makes the car subject to impoundment and the driver subject to imprisonment and/or a fine. You can only drive a car with foreign license plates if you have an international (non-Mexican) driver's license.

ANOTHER IMPORTANT NOTE:  As with any country, the laws can change.  It is best to check out the most recent rules and regulations at your local Mexican consulate -- http://embassyofmexico.org

THE EARLY BIRD… Mexican border crossings get crowded as the day proceeds.  It is suggested that if you can approach the crossing early in the morning, your transaction will go much easier than if you cross during the rush of the day.  Just a hint!  


AUTOMOBILE INSURANCE WHILE IN MEXICO

It is important to note that any automobile insurance issued outside of Mexico isn’t valid in Mexico for bodily injury, and is iffy for collision.  That is why it’s important to buy a policy for Mexican car insurance before you bring your automobile into the country.
 
Mexican car insurance can be purchased online, or at the border.  An interesting note is that if you are involved in an accident while driving in Mexico, the police generally do not get involved.  If both parties are insured, insurance information is traded, and the insurance companies deal with the matter from there.
 
If you plan to rent a car while in Mexico, is it important to purchase the Mexican car insurance.  Do not rely on your credit card insurance, especially if you are involved in an accident.  You may be denied exit from Mexico until the damage that has been done is paid for.

BUYING A CAR IN MEXICO
If you have an FM-3 or FM-2 visa, you may purchase and register a car in Mexico.