Mexico actually has a bunch of racing. I was there to work the CART events at Mexico City last year and Monterrey the last two years. Got to meet a bunch of the local F&Cers.
There are at least five or six other tracks around the country, besides the big ones at Fundidora Park (Monterrey) and Hermanos Roderiquez (Mexico City). They seem to have a fairly active club racing scene, one of those groups was a support race for CART.
They also have a couple of semi-pro series --Mustangs and (I think) a couple open wheel groups. Don't think they race too much during the summer, too hot.
I haven't a clue as to a website, try a few searches (hope your Spanish is passable).
Everybody there couldn't have ben nicer, a great bunch of people. Are you moving or visiting there?