Mexico City freeway cards

Years ago we bought ours at Sanborns in Mexico City. If I remember correctly, though, you ca buy it at the casetas on the Freeway. They used to have modules. Ours was "IAVE". Doing a quick research, I find these two options, not sure what the difference is:
http://www.capufe-iave.com.mx
http://www.viapass.com.mx/viapass/web_home.aspx

Good luck!

Hello all.

I have the crazy desire to drive to Mexico City and try to deal with the freeways there. I'm not looking to be talked out of it.

The freeways there have entrances at odd places that are only accessible if you have a particular type of card. On the East Coast, we have a similar system known as "EZ Pass."

Does anyone know where and how to obtain these cards? Mexico City driving is an "experience" under the best of circumstances and takes a lot of patience and sense of humor (OK, it's a nightmare) if you can't use the freeways.

I'll poke around on the Mexican government's websites to see if I can track it down and will report back if no one knows.

A few years back we intended to drive right through DF on our way south to Oaxaca. The traffic was so bad starting maybe 50 miles/80 km north of DF Centro that we took an exit and ended up in Toluca. From there it was south to Taxco, Acapulco, then the Oaxaca coast and ultimately up to Oaxaca City, etc.
I'm a city boy, accustomed to city traffic, but I would never take my vehicle anywhere near DF again. It'll be the bus for us.
Buena suerte.