What makes SCCA Autocross different from other forms of motorsport? Six items come to mind.
Getting It Done In Three All National Tour events have new courses which racers may walk, but not practice. Each of only three runs is for time and only the best run counts. Regional racers are often dismayed at their first national event when encountering the difference between learning a course in six to eight runs, as is common at regional events, and reaching your potential in three runs at a national event. Some regions run a “Pro” class where only the first three runs count in order to foster the capacity needed to compete at the national level.
Lack of Corner and Edge Definition Modern autocross courses have a unique characteristic in having ill-defined “track edge” limits. (This may not have always been the case.) Multiple line choices become available for different classes of cars while drivers are required to decide where a corner begins and ends, its proper radius and where to create apexes where only some (or none) of these features are rigidly defined by cones. This situation requires a skill set not normally developed by racing on traditional “ribbon” race tracks.
Extreme Feature Connectivity Courses often have multiply-connected features at a level not typically found on fixed race tracks. Such connectivity requires making complicated, multi-variable decisions to obtain the highest possible average speed from the start to the finish.
Urgent and Intense Mental Discipline An intense mental planning discipline in the limited time during and after the course walk and between runs is required based on imagining how the course will drive on the first run and then analyzing mistakes and considering alternatives to get faster on subsequent runs. To win you usually must be fast on the first run and faster yet on each run thereafter.
Both Intuitive and Theoretical Drivers Can Win Intuitive racers who drive what they feel and see based on experience are on an equal footing with more analytical types, allowing room for different approaches, as long as the first differentiator in this list is obeyed.
The Class Structure Supports Both Drivers and Builders The sport provides success paths for both drivers and builders and all mixtures in between by classing regular production automobiles at various price and performance levels as well as special-purpose racing machines at various levels of modification, performance and build uniqueness.