I've been autocrossing for a while now. Mostly in a fully prepped CSP miata and only recently with the Cayman S. Here are some of the local clubs:
The best location to autocross is in Buckingham Airfield in Ft. Myers. Well worth the drive. Here is the link to GCAC (
http://gulfcoastautocrossers.com/). Saturday is the autocross school (I'm one of the instructors) along with test and tune (there are two lots). Sunday is the competition which is held on a bigger lot. The next event is November 4-5. Events are usually held on the first weekend of each month. Most people stay overnight on Saturday. I highly recommend the school since you are likely to get the most runs and will run on two different courses.
Equippe Rapide ("ER") (
http://autox.carlc.com/) also puts on some great events in Miami. They usually run in Hialeah and Homestead on Sundays.
Of course, check out
PCA in Miami as well (
http://www.goldcoastregion.org). they usually run in the same locations as ER but they try to stay closer to Ft. Lauderdale.
There is also CFR (
http://www.cfrscca.org/) click on Solo II. CFR used to run alot at Ft. Pierce but they lost that location. Now they stick to the Gainesville and Sebring areas.
If you decide to make the drive, feel free to e-mail me with any questions at:
jjalemany@hklaw.com.
Cheers,
JJ Alemany