The Banjercito (the place that sells the car stickers) is supposed to accept a bill of sale from a dealer, if you just bought the car (say in Texas) do not have a title OR registration in your name.

In 11 years of crossing the border, I have not tested that proposition myself.

Some of my friends, however, have used the bill of sale on the back of the title, where you sign it over to a new owner, but they were obligated in Ojinada and Juarez to have the bill of sale--on the title-- sworn or approved by a Mexican notary (notario) at the border--for an extra fee.

Each border station may interpret the rules differently.

When entering Mexico for the first time, you must follow this procedure:

1. obtain your tourist visa or tourist card (FMT) -- ask for 180 days, if there is a question.
2. go to the Banjercito office with:
--FMT visa and a copy (there will be a copy booth nearby)
--your passport and copy of main page
--your diver's license and copy
--the title OR registration and a copy
--a major credit card
optional
--permission to take a rental, leased, or car with a lien (loan) into
Mexico

3. after the cleck processes your paperwork (think DMV), you will sign the temporary import permit twice on the back and then sign the credit card voucher.

The credit card voucher constitutes a lien on your car only. If you do not bring your car back across the border (or extend the permit), your card will be charged $200-400, depending on the age of the car/SUV/pickup/RV, and you will not be able to import another vehicle.

4. After you sign, the cleck will give you the termporary permit (green form), with a hologram sticker attached, and show you how to remove the sticker. Do NOT remove it yet

5. Go out to your car, remove the sticker, and apply it--carefully to the inside of your windshield, right behind the rearview mirrow. The sticker is very sticky and cannot be removed in one piece on it attaches to the windshield. Keep the green form in the glove compartment, as it will be checked down the road. It is always best to keep your passport or offical ID card handy.

You may add a trailer and one motorcycle for each person in your vehicle to the temporary permit.

6. Protect the green form and the windshild sticker. You must have both while in Mexico and when re-entering the USA. Stop on the Mexican side of the border to have the hologram removed--carefully-- and get a receipt for it. If you do that, you will be able to return to Mexico with that or another car. The trailer and any motorcycles must be with you when you "clear" the permit.

DO NOT ACEPT THE HELP OF ANYONE HANGING AROUND THE MEXICAN CUSTOMS OFFICE OR BANJERCITO IN ACQUIRING A STICKER OR PLACING IT ON YOUR CAR.

The temporary importation permit allows you to drive the vehicle and any member of your immediate family. It also allows anyone else to drive your vehicle, while you are in it. Supposedly, only the Federales or Mexican Customs Agents may enforce these rules, but some local cops have been known to get into the mix.

You may also get the permit and sticker on-line at Banco Nacional del Ejército Fuerza Aerea y Armada, if you know how to disable your popup blocker in your browser, etc. If you do not know how to do that, get your nephew to help.

I do not recommend taking a car with temporary tags or no front tag into Mexico.

There are Mexican Customs and Army checkpoints throughout Mexico that will check the permit, and may search your car. Smile.