Read about the race outline and rules here.
S-Tai races are divided into classes according to engine displacement and drive system: ST-1 (displacement greater than or equal to 3,501 cc), ST-2 (4WD, displacement from 2,001 to 3,500 cc), ST-3 (2WD, displacement from 2,001 to 3,500 cc), ST-4 (displacement from 1,501 to 2,000 cc), and ST-5 (displacement less than or equal to 1,500 cc). In 2011, an additional class, ST-X--renamed the GT3 class in 2012--was added in which FIA GT3 cars can compete, for a total of six classes. All cars race simultaneously, but contend for victory in their respective classes. So you can see battles everywhere characteristic of mixed-class racing, with cars of larger displacements having to deal with cars from lower classes and cars of smaller displacements having to let cars from higher classes pass without taking a loss. There are a variety of strategies, and, depending on the vehicle, it may be fuel consumption that is the focus, or it could be achieving the best race time. As is typical of endurance racing, there are cases when machines drop out mid-race, so you have to watch through to the very end.
The race format is based on endurance racing, with 3-hour, 5-hour, and 7-hour (the longest) races. The 6th round, to be held jointly with the WTCC, is an exception, with three 40-minute sprints. Except for the 6th round, teams are obligated to take pit stops and change drivers at least twice in each race.
As in SUPER GT and other high-level domestic categories, there are pit walks and other events during race week. There is an extraordinary number of participating cars and drivers, and fans can look forward to races with both professional and amateur drivers. This is the charm of S-Tai.