Picture a big parking lot. No, bigger. Now take out the light poles, curbs, etc.
Now add a "race course" oulined in traffic pylons, entirely inside the parking lot.
Add 3-5 dozen raving maniacs, all trying (one at a time) to drive a car as fast as humanly possible around that "race course". There are never two cars on the course at the same time, except when it can be set up such that they never get close to each other.
Stir vigorously.
Since the events are held in parking lots, the courses tend to be pretty small. They also tend to be rather windy, with a lot of pretty tight turns. Most are run in 2nd gear, though 914-4s with their low gearing wind up in 3rd gear pretty frequently. Most cars will never get over 70 MPH in an autoX.
To put it another way, it's the most fun you can have in a 914 unless you are very limber and quite an exhibitionist!
It's most of the thrills of racing, with almost none of the risks.
--DD