a course is set-up in parking lots usually. the course is marked by cones and chalk. you are timed from point a to point b. cars are sent out about 15 seconds apart. there is no side by side or passing allowed. if you do get too close to the car ahead of you they will red flag you and you get a re-run. you are classed according to you mods and tires. open track you have 10 - 20 turns on a 1 1/2 -3 minute course. autocross you have about 40 turns on a 40-90 second course. autocross is much more intense and the speeds are usually from 20-65mph where as open track you could get as high as 140mph .