Mexican Tourist Card or Permit Is An FMM, Not A Visa
You need a Mexican tourist card (FMM) to Travel Beyond the Border
You do not need a Mexican visa to travel to Mexico as a tourist if you are from the USA or Canada. You need a Mexican tourist card, (it used to be an FMT, but now is an FMM Forma Migratoria Múltiple) if you are traveling beyond the border region for more than 7 days. Although the cost of your Mexican tourist card (FMM) varies and does go up periodically, a Mexican tourist card will set you back about USD$22-$25. I got my last (late 2013) tourist permit for about $22.
You do not need a Mexican tourist permit for Baja pr a car permit.
Your car permit to drive in Mexico is another document you will need if you are driving in Mexico beyond the border.
Although the nice Migracíon (immigration) officials will tell you to pay for your Mexican tourist card at any bank in Mexico, try to pay for it then and there to avoid problems. I always do. If you are getting a car permit (and otherwise why would you be reading this website?), you can pay for the all your family's tourist permits and your car permit with a credit card (VI, MC only).Road Trip Essentials
Migracíon (immigration) keeps an accurate record of all tourist permits. Be sure to turn your tourist card (FMM) in to a Migracíon office near the border. Finding these is a challenge, but worth it. Hacienda kiosks are usually near (but not on) the bridge or border crossing. The toll-takers on the bridge cannot take your tourist permit. Since you have to turn your car permit in anyway, find the Hacienda office and turn them both in at the same time. How, you ask? Ask at the 21 kilometer checkpoint. At some point there is a customs/immigration checkpoint -- for those entering Mexico and sometimes for those leaving). If no one is on your side of the highway park, walk across the highway (everyone going the other way has to stop anyway, so there isn't a lot of traffic) and ask the guys on the inbound checkpoint where to return your permits. The next best way is to ask a cop, or better yet, a highway patrol officer for, La casita por los tramites por los extranjeros.
If you do not turn in or cancel your FMM or tourist card, you will incur fines and be denied entrance to Mexico later. See my story about the fines you will pay if you don't return your FMM tourist card. The solution is also there.