I did a Google Translate of the info. I misunderstood what I was told - or the person who told me may have misunderstood. I thought vehicles with US or Canada plates were simply exempt from the Hoy no Circula. Apparently you do have to apply for a permit. The permit is free and can be done online. For those who do not understand - this only applies to restricted driving days around Mexico City DF - not the rest of Mexico - and it only applies during the "holiday season" between Nov 1 and Jan 8. Here is a Google Translation of what can be found online........
http://www.paseturistico.df.gob.mx/pasetur/
The tourist pass is free , to foreign or foreign vehicles is granted the Federal District and State of Mexico, to allow unrestricted movement, being exempt from the provisions Hoy No Circula program .
THE TOURIST PASS DOES NOT APPLY IF DURING ITS TERM IS DECLARED AN ENVIRONMENTAL CONTINGENCY
League to meet air quality in Mexico City: http://www.aire.df.gob.mx
INSTRUCTIONS FOR TOURIST PASS:
It is necessary to have an e- mail and have on hand the registration certificate of the vehicle.
Register your email .- When you register your email (it is recommended that the vehicle owner's email), the system will send a link to access the email I record.
Log in to access the league sent to your registered email .
Fill your personal data registration .- When recording data, the system will send a password to the registered email address.
With your email and password to enter the system .
When you enter the website , you must enter the access code (found in a green box on the right side), write your email and enter the password that was sent to your email.
Car registration .- Register your (s) vehicle (s) with the data found in the circulation card. By capturing the plate only use numbers and letters, blank spaces.
Generate tourist pass .- Arrange his pass indicating if required for 7 or 14 days (choice of 3 days, you will be granted only on long weekends). It is necessary to generate the pass from the date the vehicle is driven in a municipality of the Metropolitan Area of Mexico, with the data entered into the system two tourist passes, one issued by the Federal District and one will be generated by the State from Mexico.
Print tourist pass .- After generating his pass to click Print TOURIST PASS.
This tourist pass can be obtained once per semester for a period of 14 days; or, twice every six months for a period of seven days each.
The tourist pass for 3 days will be granted only in official long bridges and authorized by the Directorate General of Management of Air Quality.
If the vehicle data, concerning the model year, plate and by country reflected in the Tourist Pass, do not match the data in the card of the vehicle, DOES NOT APPLY , so the vehicle will be liable to a fine of $ 1402.00 (Mexican Pesos), corresponding to 20 times the daily minimum wage in the MCMA.
CAN NOT CREATE PASS:
VEHICLES BUSINESS, GOVERNMENT, SCHOOL OR FOUNDATIONS.
VEHICLES WITHOUT PLATE (WITH "permission" of movement).
If this is your first time entering this system, you must create an account to use.
IMPORTANT = = The tourist pass is issued only to vehicles PARTICULAR from 2000 to 2016 models. The car Morelos, Hidalgo, Puebla and Tlaxcala can not get the tourist pass. The "Pass Resort Paisano" only to foreign vehicles registered will be awarded in the US and Canada for private use gasoline, no more than fifteen years old and have the authorization or permission from the relevant authorities for legal permanence of their unit during the winter season in Mexico which comprises of November 1, 2015 to January 8, 2016.
In my original post showing the Wiki quote - they apparently have it wrong.......
Wiki says.........
https://en.wikipedia.org/wiki/Hoy_No_Circula
During part of early December to early January, Mexico City and Mexico State participate in a special program with the federal government called the Programa Paisano. One part of this program permits, without any special pass, for foreign-plated vehicles regardless of model year (those with plates from other than states in Mexico) to pass freely through the metropolitan area without regard to the Hoy No Circula program.